If you only signed a co-applicant agreement as opposed to the actual lease agreement, then you would have no liability under the lease agreement if your mother is unable to pay the rent for the premises she is occupying at the mobile park. I suggest that you carefully read the written agreement that you signed in that its terms will control what obligations you signed on to.If you signed the lease agreement for the premises that your mother occupies, then you would be liable for past due rent if she is unable to pay the rent.