Girlfriend's Parents

My brother is meeting his girlfriend's parents for the first time on his girlfriend's birthday. They're having dinner at her parent's house and my brother wants to bring something. However, he has no idea what to give his girlfriend's parents during their first meeting. Of course, he wants to make a good impression but do not want to appear too assuming or boastful. I couldn't think of gift ideas right now and I hope to get your help on this.