It was an outstanding movie, but I got the impression her death was suicide. She walked, or fell, into the river and drowned after months of agonizing over her crime (murder). And it was Burstyn’s estranged son she’d been helping. (Estranged because he was suffering from PTSD after service in VN.)
Anyway I remember going home crying over the ending because I thought it was so unfair.
But, I saw it a long time ago, and I could very easily have gotten details mixed up. It was a little fuzzy in the story in the first place, as I remember.
I thought she died trying to get to where the brother was hiding out in the woods, and possibly get the money that he had inadvertently taken. The money was in the bags out behind the house, and his sister, the cafe owner usually left food for him there, in bags. The mean brother in law of the cafe owner was accusing the girl of having stolen from the cafe owner, assuming that everyone else would go along with him, and turn on her.