The Bridgeway Bible Commentary tries to harmonise the resurrection accounts in the following way (sorry this is a long quote):
Morning of the resurrection (Mt 28:1-15; Mk 16:1-11; Lk 24:1-12; Jn 20:1-18) It is not surprising that there are differences in the
accounts of what people saw on the Sunday morning when Jesus rose from
the dead. The sight of the empty tomb and the heavenly messengers
produced a mixture of reactions - excitement, joy, anxiety, fear,
wonder. There was confusion as people rushed here and there to tell
others. One writer records what he heard from some, another what he
heard from others. But there is no variation in the basic facts: the
tomb was empty and Jesus had risen. The following summary suggests the
possible order of events.
At the first sign of dawn two groups of women set out from separate places to take spices to anoint the body of Jesus. One group consisted
of three women (Mary Magdalene, Mary the mother of James and Joses,
and Salome the mother of the apostles James and John). The other group
consisted of Joanna and some friends (Matt 28:1; Mark 16:1-3; Luke
The group of three women arrived at the tomb first and found the stone rolled away. Mary Magdalene panicked and, without seeing the
angel or hearing the voice, ran to tell Peter and John that the body
had been stolen (John 20:1-2). But the other Mary and Salome remained.
They met one angel sitting on the stone outside the tomb, and another
sitting inside the tomb. Upon hearing that Jesus had risen and desired
to be reunited with his disciples in Galilee, they rushed off to the
place where the apostles were gathered, eager to pass on the exciting
news (Matt 28:2-7; Mark 16:4-8).
Meanwhile the Roman guards fled the tomb and hurried across the city to tell the chief priests what had happened. These priests were
the ones who had set the guard in the first place, and their purpose
was to prevent Jesus’ followers from stealing the body. Now the same
priests bribed the guards to spread the story that Jesus’ followers
stole the body while the guards slept. The priests had earlier been
worried that Jesus’ disciples might deceive people, but now they
themselves were the deceivers (Matt 28:11-13; cf. 27:62-66). If Pilate
heard the story of the guards sleeping on duty, the Jewish leaders
promised to protect them by bribing Pilate (Matt 28:14-15).
Back at the tomb, a few minutes after the first group of women had departed, Joanna and her friends arrived. They went inside, met two
angels, heard the news of Jesus’ resurrection, and hurried off to tell
the apostles (Luke 24:2-8).
Soon after the women left the tomb, Peter and John arrived, went inside and saw the linen cloth lying neatly folded. They believed the
evidence they saw that Jesus must have risen from the dead, but they
left the tomb confused, not understanding the significance of the
event (John 20:3-10; Luke 24:12).
Mary Magdalene, who followed Peter and John back to the tomb, arrived after they had left. She remained there alone, weeping. Then
she saw the two angels inside the tomb and, on turning round, saw a
man whom she did not immediately recognize (Mark 16:9; John 20:11-15).
When she discovered that the man was Jesus, she took hold of him as if
not wanting to let him go. Jesus told her she had no need to cling to
him in this way, as he was not ascending to heaven immediately (though
he would within a few weeks). She should not become dependent on his
physical presence, otherwise she would be disappointed again. She was
to go and tell the apostles what he had told her (John 20:16-17).
Shortly after appearing to Mary Magdalene, Jesus appeared to the other women of her group (the other Mary and Salome) as they were on
their way to tell the apostles of their discovery (Matt 28:8-10).
The two groups of women reached the house of the apostles about the same time, followed soon after by Mary Magdalene. They told the
apostles of what they had seen at the tomb and of their separate
meetings with the risen Jesus, but the apostles believed neither Mary
nor the other women (Mark 16:10-11; Luke 24:9-11; John 20:18). (All
the events summarized in sections 1 to 8 above probably happened
within the space of an hour or so.)
The Treasury of Scripture Knowledge on the angles in Mark 16:5 says:
This appears to have been a different angel from that mentioned by
Matthew. The latter sat in the porch of the tomb, and had assumed a
terrible appearance to overawe the guard. (Mt 28:1;) but this appeared
as a young man, within the sepulchre, in the inner apartment. The two
angels spoken of by John (ch. 20:11) appeared some time after these;
but whether they were the same or different cannot be ascertained; nor
whether the angels which manifested themselves to the second party of
women, recorded by Luke, (ch. 24:4,) were the same or different.
Matthew Poole on Mark 16:5 concerning the number of angels says:
Both Luke and John mention two angels in the habit of young men.
Matthew speaks of one sitting upon the stone. They might see him
sitting upon the stone, and yet find him within also, the motions of
angels are quick and undiscernible to our sense, or the stone might be
rolled inward. That they were affrighted is no wonder, considering how
apt we are to be frightened by any apparitions.
John Gill on Mark 16:5 on the number of angels says:
nor is this any contradiction to John's account, who says there were
two angels, one at the head, and another at the feet, Joh 20:12; since
Mark does not say there was no more than one;
John Gill on Matt 28:2 on the angel says:
This posture of the angel does not contradict what other evangelists
say of this, and the other angel, that they stood by the women, and
also were sitting in the sepulchre, Mr 16:5, for each was true: when
the women first came, the angel sat upon the stone; after that, with
the other, stood by them; when having invited them to the grave,
placed themselves, sitting the one at the head, and the other at the
feet, where the body of Christ had lain.
Interestingly the The Pulpit Commentary on Luke 24:4 and the number of angels says:
To one company of women one angel appeared: to another, two. Mary
Magdalene, a little later, saw two angels in white sitting, as it were
keeping watch and ward over the sepulchre for a short time after the
sacred form had left it. The words which these beings from another
sphere spoke to the mourning women were slightly different, but the
teaching was the same in each case: "He is not here, but is risen. Do
you not remember what he told you when he was yet with you?" Van
Oosterzee and Farrar repeat a beautiful passage from Lessing on this:
"Cold discrepancy-mongers, do you not, then, see that the evangelists
do not count the angels?... There were not only two angels there were
millions of them. They appeared not always one and the same, not
always the same two; sometimes this one appeared, sometimes that;
sometimes on this place, sometimes on that; sometimes alone, sometimes
in company; sometimes they said this, sometimes they said that."