Well, I can sure understand you wanting to leave the cold behind in Pennsylvania. I am originally from Ohio, and now live on the Gulf Coast. I have no intention of ever leaving the Southeast. And North Carolina is a beautiful state.
Now, when I was married, I had my mother-in-law move in with my wife, stepdaughter, and myself. She lived with us for four years. She didn't need to move in with us; she wasn't sick or anything like that. And I just loved her and we got along famously, but the house never again seemed to me like the home my wife and I had created. So, this is strictly my opinion, but I wouldn't recommend moving in with relatives, if it can be prevented. A suggestion would be to get a mobile home and put that up on your mom's property, if that is permitted in her location. It might take you longer to save-up to build a house, but at least when you locked the front door at night, it would be your husband, son, and you, in a place that was your home. It would also give you the chance to determine if you want to live that close to your mom, without the expense of building a home and then maybe deciding not.
Just a suggestion for escaping the cold. The best to you and your family, MK!... Chuck