I received the OP's message which I think she wanted to convey here, which is along the lines of not being satisfied with this answer given by disagreeable. There might be one possible item that might help but it won't get you the remedy you want. My entire post is based upon the limited facts you provide:
Unfortunately, it seems that disagreeable is right, even if it's not "justice" or what the OP wants to hear. I'll assume that all the "conditions" that were agreed upon were not documented in writing which would limit the ability of the new property owner to convey the home. If your daughter is somewhat mentally disadvantaged, it would seem foolish to provide her with an expensive home without any agreement limiting her right to transfer. How here's the next question - if your daughter is mentally deficient, you might have considered trying to void the transfer based upon your daughter's incapacity. That will not be easy to do, especially since you transferred the home to her without exception. You can always report the theft of your belongings to the police.
Without knowing ANYTHING about the case other than what I read - here is the only possible remedy you may have. You would appear to have no cause of action. You voluntarily transferred the home so you have virtually no rights except possibly for an "easement" - a right of access/use of the property. Typically that would require recording in the county records office or as part of the deed of sale to your daughter but there are exceptions. In California:
Implied easements: An inference drawn based upon the intent of the parties upon conveyance of title (to the property) in cases where there is reasonable necessity of use. (Probably not applicable, this is usually where land is virtually surrounded and requires using the property of another for necessity.)
Prescriptive easements: The continuous, open and notorious, easily observed use of the land for 5 years or more.
Perhaps you'd have an ability to park your mobile home on the property if you've been there for five or more years. You can try to fight it in court. Perhaps you can
call the state bar and someone may provide you with assistance. But other than that, the cost to an attorney would be prohibitive to fight your case and litigate. This may not be a simple appearance - you need to locate your daughter and the bad boyfriend, subpoena them and cross examine them, etc.
Best of luck with this situation and I'm sorry that your best intentions resulted in this.
