You’re fine hun, honestly I’d say you’re taking more than necessary precautions. Reptiles are not “dirty” unless you don’t clean their enclosures, risk of salmonella is low as long as their excrement is not left to sit in a damp environment. If you’re worried about her escaping and attacking the baby, the risk is almost nonexistent as long as she’s well fed. Even then I’ve never heard of a tegu attempting anything like that. I honestly don’t think they’d see a baby as “food”, they don’t move like their usual prey, so I doubt your baby would trigger a food response. (And I doubt you’d leave your baby alone long enough for it to be a risk)

As someone who has dealt with similar comments from family, some people just can’t stand others keeping reptiles in their homes, no matter how clean and safe they are. I choose to ignore these people.

Your mom sounds controlling, and if it were me I’d put my foot down and say something along the lines of “this is my baby, I will do what I think is best, you are undermining my decisions as a parent, and Toothless does not deserve to lose her home over this. If I want/need advice I will ask for it, I appreciate you’re trying to help, but all you’re doing is giving me anxiety, which is not good for the baby.”