They are rapid racists who drop the n-word like no one's business.
I know it's a typo & I don't usually pick on typos, but I thought, "Rapid racists are so quick to drop the n-word, you can't get your daughter out of there fast enough."
I'm afraid I don't have any useful advice avoid racist relatives. I have some relatives like that myself, but I don't have children, so I don't worry about "catching" anything from racist relatives. If I did have "virgin ears" to protect, I'm afraid I would say the same thing I would say to someone who swears constantly, "I don't want my child to learn those words/attitudes."
Oh, the irony of attending an African American history conference while avoiding racist relatives. Yeah, you wouldn't want to stay with them. The dinner conversation would be awkward, to say the least.