If the manufactured home really became attached to the land, then you would need to execute some sort of deed to transfer it to your mother. Probably most advantageous for you would be a quit claim deed. You prepare it and have it signed in front of a notary granting ownership of the land in question to your mother. You then will have to file it (small fee, somewhere in the vicinity of $12) and pay the transfer tax I'm not seeing an exemption for a sale to your mother (had it been a gift that would be another story).
Three ways this can be done:
1. You can go to a legal forms store or website and adapt a stock form to your situation, and you and mom hope you did everything right.
2. You pay a lawyer a small amount of money to draft and record it and be fairly assured that the transfer if nothing else is right.
3. Mom could go to a title company and have the deed prepared, have a title search done, and then buy owner's title insurance so she is protected just in case there is something that is lurking unseen.
Frankly, I'd go with #3. I wouldn't take a gift of land from my sainted aunt without owner's title insurance.