To mend fences means to improve your relationship with someone you have argued with, which is what she did by making up with them.
Context: Even as a small child, she'd been quick to anger, but she'd make up and improve her relationship just as quickly.
Hypothesis: Even as a small child, she'd been quick to anger, but she'd mend fences just as quickly.

Is the hypothesis incorrect? (Yes, no, or unknown)?