There might be more to the story. Was he after her house? I have relatives in their nineties who live by themselves and are of sound body and mind, one of them moving his lawn and recently took a road trip. If anybody tried to put him in a nursing home, he might not react kindly though surely not with murder.
According to the first article posted on this, she believed him to indeed be after her wealth.
And as that article was written, it seemed she was right.
Whether it was murder or self defense hasn’t been conclusively shown, but I am inclined to give her the benefit of a doubt absent furthur evidence.
I am not willing to begin debating this with some unwarranted assumption that she was incompetent or demented os whatever. Nothing which happened indicates that.