There is a lot going on here to be honest and you brought some additional complexity into it by bringing up a dead person.

First, she doesn't need trademark to sue companies for using unauthorized statements or pictures/video of her even if it is AI generated. This is called the right of publicity.

California has a law on the books that addresses your concerns around death and it is a better solution than trying to shoehorn trademark into this problem. I don't necessarily agree with posthumous protection myself, but it is a better way to accomplish a goal.