I've known people who were very emotionally disturbed who just got in cars and drove on a whim. Miles and miles, states away.
Hypothetical scenario: Jen is volatile on a good day but the CPS visit made her crazy. Angry at the neighbors, the kids, Sarah (because the spouse is a target when anything goes wrong, right?) She orders them all to get in the car. They are all too scared of her to say no, so they get in. They take the dogs because the dogs are used to riding in the car on outings with them. Jen rants and raves and Sarah and the kids stay quiet. Or, the argue back with her. At some point, either from despair or anger, she decides to take care of her problems permanently. She see everyone in the car as a unit, or considers them all responsible for her despair or anger. So she takes them with her.