I just don't get some people at time's

My mom does home care for a few older people. Well this one her grandson has a pitbull dog. Well I heard he is very aggressive at my mom. He is growling and showing his teeth. My mom flat out told the older woman she wouldn't go into the house unless the dog is locked up or outside. After about a week of the older lady not listening to my mom about the dog she will no longer be going to that house. Tell u the truth I don't blame my mom at all.