Maybe talk to your mom first. If she really wants you to stay with her, I would at least speak to her and see if she will have it checked for the type. Like PP said, not all mold is hazardous, so it may not be a huge problem.
Most of what I read about mold, says that the only way it will harm your baby is if you eat it. Just inhaling wouldn't prove to be problematic for the baby (it might cause respiratory irritation for you).
Even the cleanest of homes can have mold in them. I would see if your mom would have it tested (if it's black mold then I would definitely stay away) and possibly have it removed before you just back out.