When trying to decide what is fair, I always like to think what the reaction would be if the "shoe was on the other foot".
What if someone shows up at the hotel they booked six months ago and was told you do not have a room because we had a death in our family and need it for our family. Here is your deposit back. Or even notifies them a couple days before they are to leave on their vacation that their reservation is being cancelled.
My belief is that when someone makes a commitmant, it is their obligation to live up to it. Circumstances not created by the other party should have no bearing on that obligation.