A.F.
You're not gonna prevent him from escaping. You can constantly get up every night and put him back to bed, or you can put up a baby gate in the door to his room, and let him learn to put himself back to bed. I did this with my daughter and son and they both sleep perfectly well through the night now. Of course, make sure that the room is as safe as you can get it, but at this point it should be anyway. Children learn that there is no one up at that time to play with them, and eventually head back to bed on their own. You might find him asleep on the floor a few times, so watch where you step in the morning lol. Good luck, hope this helps.