What should I do?

As an adoptee myself, I can appreciate your concern and wanting to help your friend. You are a kind person. However, this is a delicate matter and sometimes we need to take the steps ourselves as part of the healing process. You should provide him with the information and assure him that you want to help but realize that this is information that he needs to decide what to do with. He may struggle, he may contact her right away, he may keep the information tucked away for years, he may not ever attempt to contact her, but he will have it and the decision will be his. In my case, as an adult I was contacted by my bio sister this was 15 years ago. I knew exactly where my mom was, I knew she was ok, and I knew that she indeed loved me, there were circumstances that were beyond her control and she could not parent me. That was enough for me, I never met her face to face but it was enough for me. I hope this helps you decide what to do with that.