I think it is great that our first question is "what does the contract say"; God bless the Common Law and Cavite Emptor.
That said, when circumstances arise through no fault of either party that are clearly outside of the basic understandings of the parties, the intentions of the parties and the goals of the contract when it was entered into, the court has remedies/discretion beyond the words of the contract. Call it "Acts of God" but it really goes deeper into whether the ever would have been (or was) an agreement in the first place.
As to whats right? well if the contract gets really specific in time frames and events that support cancellation and refunds to the point that a reasonable person would say the parties made provision for XYZ event, then you go with the contract. If not, people can generally make their case, presumably in small claims Ct..
What morally right? Well, IMO it makes sense to recognize that the Rentor has, in many cases, made commitments based on the original rental deal too. On the other hand, for the Rentor to say to the Rentee "too bad your problem, you are past the cancellation date in the contract, I am keeping whatever you paid me". If I'm the Rentee, they better have a contract that clearly contemplated/addressed this situation to expect me to be the party who "takes it on the chin".
Everybody hates litigation of this kind of stuff. So much better to: 1) say as the Rentor "I will do all I can to get you a refund". 2)Contact whoever you are renting from for the week and pursue a refund. 3)As a Rentor pass through whatever relief I get on my cancelation in where-ever for USNA Com Week to my Rentee. If the amount returned on the 2nd rental contract is less than 50% of the Com Week rental, the two parties to the Annapolis Com Week rental to split the loss 50/50. Good Faith and Fairness, that's all anybody should pursue in this stuff.