If I were in your shoes, I wouldn't mention anything to her about renting anything. I would ignore the email completely. You are not responsible for her as she is not your mother. Your h and his siblings need to step up to the plate on this one. Your home is not a hotel/motel.
Trust me, it is better not to address this issue unless she brings it up. You don't need her living under the same roof w/you because she will take control and make the lives of all that live there miserable and she may be a problem getting rid of her when it's time for her to leave, i.e., she may become a permanent guest.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.
