Can I sue his mother's insurance in small claims court to get them to cover the judgement on their insured's son who was driving the car?

Someone hit the side of my car. He is at fault. He does not have auto insurance, but the car is insured (liability only) by his mother who does not live with him. He does not have a job, nor much assets. I sued him directly in small claims court and won a judgement; however, he is refusing to pay. His mother's liability insurance does cover him under permissive use though. However, he has not filed a claim with his mother's insurance.