The personality of that dog sounds like the personality of my stupid neighbor's dogs. They killed a number of my birds, and we are going to court over it. First of all, I would go to great pains to not let the chickens out because of that dog. Secondly, your mother should understand that the dog shouldn't be allowed to roam. It's dangerous. It kills animals, and then tries to defend its prey from humans. What happens if it goes in somebody else's yard, attacks their pet, and somebody (possibly a child) panics and tries to save the pet? It could be a tragedy, and your mother would be at fault. I hope the yard is fenced to protect your neighbors. Dogs like that should be worked with by an experienced dog person or PTS. No offence to your Mom, but staking a high energy dog out in the yard will almost always make it aggressive. Perhaps, she didn't know that. I hope you aren't in the situation long and can get a place of your own or find a solution for the dog problem.
I would also like to add that I have read through the posts and didn't see any attacks.
Good luck. I hope it all works out.