So if both parties are being relieved of their obligations, does that mean students get their money back for tuition, room and board?

If you sign up for in person instructions, and then are told they are switching you to a YouTube video, you should be offered a choice to continue on the new terms or to terminate the agreement.

If you are asked to leave your housing for part of the semester, you should be compensated for relocation expenses.

If lightning struck one small campus dorm, the student would expect the university to immediately provide alternative housing or pay for a reasonable alternative and moving expenses. The same should hold if the whole campus was closed.