This is highly dependent of the way the contract is written. I have two thoughts on the matter but if you could tell us where you are, that would help a lot.
In Minnesota, the standard real estate contract states that "the risk of loss is upon the buyer" meaning that the buyer has the option of cancel the contract if the home is damaged, but not the seller.
Second, if the contract stated that she was supposed to close in April, the closing date has passed and neither party is likely required at this point to preform. I would talk to an attorney to confirm this in your specific situation. I hope that helps.