Remus and Tonks had a son, Teddy, who of course they left behind when they died. Harry is his godfather. In the epilogue, Harry was talking to his kids and mentions that they "have Teddy over four times a week for dinner" which implies that he isn't living with them. So who is raising Teddy?

Tonks' father is killed during the war. Nothing is ever said about Remus' parents still being alive. Teddy could be raised by Tonks' mother or by Remus' parents.