I'm more inclined to the canon, that is, to 1 or 2 of her fate. Although it seems to me that Maxwell Atoms did not really think about what will happen to his characters in the future. He just created and everything. Even if the story of Grim about how he became death in many episodes diverges.
I consider the first version of Mandy to be more canonical, since in that episode this future was shown exactly as their real future. Perhaps there Mandy went out of her transitional age and became a simple intelligent woman.
The second version of Mandy was shown as a POSSIBLE future, and in it the girl did not look completely adult, her face remained the same childish, but with a caterpillar body.
About the third version, I generally keep quiet. I do not like her. She was made a whore, and this is marriage with Grim... I do not know why this version delights many, because it is not even a canon. The idea is certainly interesting, and I would consider this its future if there was no marriage with Grim.
The fourth version as we know was shown in the form of Mandy's fear. This is an unlikely future, but who knows? At least in such a future, Mandy would stop humiliating a Grim.