Did she do practice essays before the test? Does she have a study group so she can go over things with other students and see what their notes and essays are like?
In my college history classes, I was in study groups that went over material together, but some also did practice essays and made up prompts for each other. (I was sort of an amateur writing tutor along with being a paid science tutor, and would get asked for input a lot with essays and papers, which is why I remember even though it was eons ago).
If not, that is something that can be worked on with you (or an older sibling in college?) as test prep. Without other students in the same class, maybe you could find examples online. Even the AP history responses, though a different format, might help in seeing what is an adequate response vs. a suboptimal one.
https://apstudents.collegeboard.org/...stions-by-year
If not, maybe some of the vocabulary in the questions might be of use.