I enjoyed my MHC interview. The student was very nice and didn't ask any trite (e.g., "Which 3 adjectives describe you best?" or "if you had a million dollars what would you buy?") questions. She just asked about my activities and interests. I recommend going on a little "rants" about the things she loves (when prompted). The interviewer wants to be able to say that your daughter seems passionate. Also mention any unique interests. For example, I was involved in many activities, but in most of my interviews I made sure to mention working as a clown. It will probably intrigue the interviewer and lead to more conversation. She should not be afraid to talk to the interviewer in a casual (but respectful) manner. I cracked (PG) jokes and shared (related) anticdotes during my interviews, so if your daughter is good at reading people and gauging the appropriateness of a joke relative to a setting, then that's fine. The best advice I can give is to generally know how to verbalize/summarize goals. She should practice beforehand, either with you or, if possible, in an interview for some place for which she doesn't care as much. Oh, and she should be prepared to ask questions about the college because the interviewer WILL ask if she has any questions. Even if she knows a lot about the college (she should know the basics, like size of the school, etc.), she should ask a few questions. Examples: What were the interviewers favorite and least favorite things about Mount Holyoke? How are dorms assigned? How many clubs do most students join? How late does the PVTA run? and so on...
MHC doesn't offer admissions officer interviews. It probably holds about the same weight, but remember that interviews only count for so much anywhere. They help to convey interest, and anything else a person wants to express verbally rather than in her app, but the application is always the most important part.
Also, she should definitely mention that moho is one of her top choices and why she loves it so much. Good luck to her!