Not unless the contract you bought it buy stipulated that new buyers are liable for  back rent, or if the previous owner had given a security interest in or lien against the mobile home as security for the rent. (If he had, it would have shown up during your title search.) Otherwise, rent is a personal obligation; the former owner is still responsible for it, and the landlord could look for him to pay it out of the proceeds of selling the home to you--but you are not liable for someone else's debts.