Mom retouches artwork-invades privacy?

Your mom was wrong to do that, and mean to say "I want it done RIGHT" Like your not good enough. I would give it to my grandma, and tell her about what my mom had been doing. It's really unfair to you AND your grandmother, because I'm sure your grandmother wants something from YOUR heart, not just your mothers. I would confront her like you did, or even make two. One being pretty bad, so she could work on it for longer, and not on the real one.