I think you need to follow your Mom's wishes. The guy sounds like he wanting to do the right thing if he has already said he'd pay for your chickens, most jerks don't offer to do that so fast. And you're not going to get a fence from the guy, that's a little too much. Just take a deep...
Animal control would document the attack which will provide a legal written paper trail. Now before you do this, make sure your parents are okay with this (home from school leads me to believe you are under 17 yrs old).
Sometimes if a problem happens between good neighbors, things such as cops...