Mary the Mother of Jesus isn't mentioned in any of these verses. The "Mary the mother of James the less and of Joses" is a different woman.
Would you have us believe that the Gospel authors, under inspiration of the Holy Spirit no less, would not identify the Mother of our Lord as such. St. John, who was there with her, does - at the Cruxification. Look at the supposition of the find in the article. That "James son of Joseph, brother of Jesus" is important because a brothers name would only be used if he were really important. I'd say that Jesus is a really important Figure in the Gospels, wouldn't you? So even if you were to believe that Mary the mother of James and Joses, et. al. was also the same as her who is the Mother of our Lord, don't you think the Gospel evangelists would point that out and refer to her as "the Mother of Jesus"? The fact that they don't is the best proof that Mary the mother of James is not the Mother of God.
Your "tomb" example from St. Mark's Gospel is actually on Golgatha at the Cross.
In any event, why do you have a hard time assuming that Mary the Mother of our Lord would not have been at the tomb since He had already seen her. Since she, who knew Him more intimately than anyone else, keeping all the events of His Life since before His Birth and pondering them in her heart, would have known that He would Resurrect on the third day - as He made known to His Apostles (they didn't understand at the time. Scripture says nothing about Mary the Mother of Jesus not understanding). Scripture neither asserts nor precludes this fact. The early Church Fathers naturally assumed it, in fact, some argued that the Scriptures imply it - since Mary was absent at the tomb that first day of the week. That odd detail did not go unnoticed by them. It didn't make sense - unless she had already seen Him! Why would it be wrong for others to contemplate this as well? The Holy Scriptures in no way precludes this possibility. Their silence about her being at the tomb invites it.
I thought a little about this question and I have an observation that hasn't been mentioned. One of the chief reason, if not the only reason for mentioning who went to the tomb is to provide evidence of the risen Christ. Christ's own mother may not be the best witness to site as proof of the event. Further, I wondered if Jewish law which is fairly specific about number of witness, can't testify for self etc, have anything to say about mother or father as witness. Just curious.
Mary may not have been among the first to reach the tomb, but had heard what the first visitors found before she set out for it or at least before she came close to it, for a variety of reasons: She may have been staying indoors to observe shiva - an obligation not applicable to the women named in the Gospels as the first visitors, or perhaps she was staying someplace farther from the tomb than the others were, or her advanced age, or something along those lines.