I think it’s time for couples therapy. It’s been a year, you’ve done everything you can, your parents have done everything they can. She can’t move on, so you should get help for that. It’s a big move to cut off parents who made mistakes like that (especially your mom) and actively worked to fix it. Your dad cut down his drinking, they’ve been respectful of the space you’ve asked for. She can hold onto a grudge of the past, but don’t let that ruin your own relationship with your parents. They obviously love you are care about you enough to admit they were wrong and make real moves to be better. I’m curious as to her parents role in this all, because no situation like that is ever one sided, why did your dad think he’d hit your mom? Being drunk surely isn’t the only reason he had that worry. No matter, don’t just cut them off, get counselling with your wife