It would help to know what kind of racism she is subjected to. It's one thing to say I hate Mexican food and another thing to say I hate Mexicans.
"showing or feeling discrimination or prejudice against people of other races, or believing that a particular race is superior to another."
If she attends a school with a racial mix of students, as we have here in the USA, it is important that she is not overly influenced by her apparently racist grandmother and new husband as well as her mother. Such people use race as a way to shore up their perceived importance.
If these folks were still highly opinionated re the JW religion I would imagine you would limit her contact with them. As the witness beliefs are very dangerous as well as opinionated.
If they are as stupid as they sound, if it was up to me, I would seek to protect my child from crude and rude behavior.