My mother in law cannot mind her own business.
Yikes! You got one of the bad ones. They sure makes things hard. 
She really does - she is always trying to bend my husbands' ear to her way of thinking we should do things - with our house, our kids, etc.. and she never listens when he tells her that's enough.
Maybe he needs to break away from her a bit. Maybe then she will mind her own business. 