Tell your mom that your bunny is not a wild rabbit, and that he is not equipped to survive in the wild. He will be more unhappy because he will have a strong biological urge to reproduce, but no way to do it. Is it not worse for him to be emotionally frustrated than neutered?

We know you will love him and I am not posting this to upset you. But that's just something for her to think about.

Go to http://rabbit.org if you need more info. Not trying to cause trouble, just want her to have all the facts.