So I feel like the information you're sharing is very inconsistent with each of the comments. In your original post, you made it sound like the car was under operation by the mother/grandmother and that it was in good standings in terms of insurance except that your niece was no longer on there. If the car was being stored and not operated, and only had enough insurance to protect it in its parked place, then it is no surprise that the insurance company is not willing to cover for the damages that was caused while in operation.