Omelettas dad was abusive and would beat Omeletta and her mother often.

Phantom: To be honest, I don’t even remember how my dad was like… my parents died when I was 6.

Omeletta eventually got tired of her dad's abuse and tried to teach him a lesson. She ended up accidentally killing him. She didn't mean to kill him, but she doesn't miss him at all. Omelettas sweet mother peacefully passed away in her sleep one night after her long and quiet life.

Well, there goes my storyline for the hunter having an abusive mom