That is a difficult one. It would be helpful for them to sign an agreement that requires them to move out when necessary and that gives someone else the ability to make the determination of when it becomes necessary. The problem, of course, is what will you do if they refuse to move? At least you will have a better argument with the agreement in place ahead of time than without an agreement at all. It's also important for your mother to give you her durable power of attorney or to place the house in trust so you have the legal authority to evict your siblings if it comes to that.