what executor to will has to do once person in the will dies
First off your husband and sister will have to make sure all their father’s bills are paid off with the estate. Secondly they will need to have a contract drawn stating who gets what and that the money recieved for selling off their father’s house will be split evenly. Once they both sign this contract and get it noterized they will both need a copy. After this your husband will be incharge of selling the house because he is the "Executor of the Will" for his father. Also please note that if there is anything else that is going to be sold or divied up that all this will also need to be put in the contract unless it was "Willed by name" to one of them.
I hope this has been of helps.