First, where in TX is this place, as the Winters can be bad. In 1995 we were in Lake Travis just above Austin and it was in the high 20's so we went to San Padre Island, (and that's about as far South as you can go), and it was still below freezing,( ice on the Palm Frons). That being the case heat is needed and not cheap in and RV due to the thin walls. So before you do it, look for alternatives. The other thought is let Mom off the hook and get some public assistance and they will pay for housing, food and health care. Go to your local Social Services and apply. As far as the gardening, yes do it, and that can be done in Municipal gardens that are open to residents that have a section for themselves or share crops. Good luck, but get real and use the available assistance, it's there for you.