Should I make the ending ambiguous or one of the following?

Ambiguity can work as an ending but it can be very frustrating if not done properly. Personally I would have the daughter caught in the act of possibly trying to kill her father at the end. Someone arrives on the scene and manages to stop it from happening - you could then be a little ambiguous as to whether or not she goes to a mental institution or whether the father decides that he should finish her off either because he loves her and doesn't want her to be locked away forever in an asylum or because he hates her and wants revenge. Whatever you decide good luck with your story and your ending.