Legal Question in Real Estate Law in California

Based on the information given, I'd have to say that the transfer by gift is presumably legally good, and the brother-in-law presumably has the right to sell the house and pocket the net proceeds. However, there is a slight chance that for some reason the gifting process wasn't properly done and could be voided, e.g., maybe "undue influence" could be shown, although this isn't established or shown by any of the given facts such as mother's current incompetence. As far as your rights as the current occupant go, which are different from any rights connected with the gifting of the house, that'll depend upon whether other facts show your status to be that of a guest, tenant, trespasser, etc. The rights of each class of occupant are quite different, and may be affected by local law. I'd suggest an initial (perhaps free ???) initial consultation with a local lawyer who can check the property records in your county.