To give my thinking, OP:
If DD is registered with Disability Services and/or already receiving exam and/or coursework mitigations, I think she can bring that to bear in the present situation. If she is registered with DS she should write to them directly. She should not necessarily expect a reply for a few days, because many university staff are on leave this week and will then have a backlog of email to work through. If DD is not registered with DS but receives mitigations within the School, she should approach her Teaching and Learning Officer (or whoever organised the mitigations) from the disabilities perspective.
Again it is crucial that she understands the guidance. If it suggested that students spend no more than, say, six hours on each exam, then even with extra time my university would expect her to do one exam each day. My strategy only has a chance if there is an expectation that students have the better part of two days to devote to one exam.
As final year students usually have many optional modules I would also ask how DD can be so sure only a handful of students are affected? Might others not have in-person exams at some point during the 48 hrs?
Assuming DD is either registered with DS or receiving mitigations in School: if the guidance is as loose as has been suggested and only a handful of students are affected, I would expect DD’s approach to result in a solution for all of them and extra time for her. If loads of students share the conflict I would expect extra time for DD on the basis of disability, but not a general solution.
If DD has not been working with DS or her School regarding her disabilities, unfortunately it is not clear what will happen if she initiates a relationship now. But it could be useful for her final term.