This is an old movie from the 70's I think?

A women is hanging out and having a dinner party with three or four men. There is a fireplace I think. They get drunk and out of hand and they get into a struggle. The women falls and hits her head. They think shes dead, they are very scared ad put her in her car into a river only to see her wake up as the car goes into the river.She was still alive. They suffer and feel guilt; her spirit ends up coming back to kill them.Her spirit only gives up when the police pull her car out of the river years later and the dead women's mutilated skeleton reaches out and then falls on the floor dead as if her spirit had been waiting to be released.