Mom wants to sell their home and move into their mobile home in another state. How do I handle this?

By "they", I assume your dad is involved? How does he feel about this? Are they both cognitively competent? In the end they can make their own decisions, but you should try to have a calm conversation with them and help them sketch out a pro and con list. If there is a family friend they trust, bring that person in on the decision (if your parents say it's okay). A banker or financial person would be ideal, as well. You are right that this should not be done lightly, but maybe they have good reasons for wanting to make this move. Try to talk it out and see what those reasons are.
Good luck,
Carol