Best therapy? Just listen and be a friend.
He has now passed away, but I had a friend who had seen serious action in Africa in the French Legion. I met him when he had just made it back (read: totally *not* ready for society), and I immediately got on with him. I lost count of how many nights we spent talking and drinking, but eventually we got some of the demons to settle. You cannot erase memories, but you can help people accept them as part of the past, not of the future.
Personally I think it's criminal to fob off returning soldiers with pharma, that's not what they need and very poor payback for them risking their lives.