I think there were more than three women. It looks like they have either visited the tomb in groups or as singles, either at different times or at the same time. If they were in groups it is also likely that the writer chose certain women represetatives based on their knowledge.
None of the verses speaks of these three being the only persons to travel to the tomb.
Thank you! I looked it up, but wasn't sure because each book mentioned different people. I knew that all the accounts are true, I just got confused. Thank you for your help! :-D