To mend fences means to rectify a damaged relationship, which is what she is trying to do in the context.
Context: The only question was, how would she repair the relationship with him, and would he want her back after she had seemed to side with uncle hugh?
Hypothesis: The only question was, how would she mend fences with him, and would he want her back after she had seemed to side with uncle hugh?

Given this context, is the hypothesis true (Yes/No/I don't know)?