Have you thought about renting the house out at least temp and try to see if someone is willing to take in both cats. Its just an idea. I hope that they will be re homed together.
I had even suggested that to her but I don't think right now they could stand seeing anyone living in their mothers house. They all took her death very hard and are having a hard time dealing with loosing her, it is recent and to fresh, their pain is to raw. To me that would be the best solution, letting them live there and just have someone move in to look after them..