Where did the OP say that there was a Hankido or Sombo school near him? Hankido and Sombo are extremely rare. It's also difficult to find Judo schools these days that teach a wide curriculum that would include no-gi, newaza, leg-based takedowns, and/or leg locks. He would have to find a freestyle judo school for that, and again that's pretty hard to find.
Additionally, if he's already taken Hapkido, taking Aikido would be pretty redundant. He can keep his skills sharp by simply continuing to practice Hapkido.
Bjj is the better option in this case. He gets the benefit of learning Judo/Wrestling takedowns, Sombo leg locks, no-gi grappling, and Bjj's ever-evolving ground game. Again, a compliment to the skills he already has. If he's really lucky, the Bjj gym will have a Judo coach on staff.
Oh and yeah, there's a Bjj school near him.