I'm not sure any scholar is absolutely sure how Mark is supposed to end in its original version. Most agree through verse 8 of chapter 16, but not everyone agrees on what, if anything that follows is authentic.
For purposes of this post, I'm going to assume that only the first 8 verses are authentic. This means Mark ended the book in a very odd way for a first century writer. He ended with women finding out about the resurrection, and then dropped the story. First of all, that isn't much of a conclusion. Second, the special people at the end are women (something you didn't do back then). Women were given this place of extreme religious honor. In essence, Mark gave the version of the story that would be least believable to most readers.
Perhaps that was the point. This gospel wasn't written as an apologetic treatise. He starts off with Jesus violating a lot of societal norms early in his ministry. Then he ends the gospel by breaking societal norms. It seems like he was trying to make a point.