I would have put my mother in my car, drove to the pet store and then taken money out of her purse to purchase me a new tank!
I can't believe your parents feel its o.k. to remove your own propierty and give it away. How old are you? If you are under 18 its a bit more understandable (but still uncalled for) but if you are over 18, then its just stealing. Plain and simple!
Good luck finding a place for that ribbon snake to live!