Deadlines are not holy. The person who wrote the deadline into the offer letter can replace it with a longer deadline- based on professional judgement.
I will ALWAYS extend an offer for a student who levels with me- aka “I am really interested in your company, but I have one more company to explore and don’t want to cut the interviewing off if it is at all possible to get an extension”. What is irksome is “I have 8 more first round interviews scheduled, and a couple of them are much more prestigious than your company so here’s the deal- if I don’t get a better offer, I’ll accept, can we pick up the conversation in a month?” (of course nobody says that- but that’s the clear implication).
But career services will likely give her the preferred messaging!