I am renting to own a mobile home in a mobile park here in Northern California and they don't have the title. The guy who lived there before died and he gave it to his sister and she gave the mobile home to the park. There was a lien on it but he had paid it off. The bank he went through closed their doors and Bank of America bought the bank. The owner of the park went in there to get the title and ask about the lien they said that there was no paperwork on it? Can they legally sell the trailer to me without the title?

No they can't. Rent to own is generally higher rent than normal, so you should be adjusting your rent back down until they obtain the title.

I agree with Joy to an extent. They cannot transfer the home to you without title. But they should be able to get title before the contract is completed. How long does it have to go?

A few issues you should look at:

The guy who lived there, died, and "gave" it to his sister: Dead people can't give anything. Did he leave it to her in his will? Was the will probated?

Did the sister give the MH park a bill of sale of some sort?

The bank that folded and was succeeded by BoA: the successor bank apparently has a lien. That they cannot find the record is their problem. The MP park needs to get them to sign off on the title, without warranty if need be (like a quitclaim deed were it real property).