My stepfather was a "Merrill's Marauder" Army Ranger. (CBI theatre)I think that if you check with this website some of the veteran's would be willing to help you in some ways to brighten your dad's room.
just follow the site and you will find search engines and a place to ask for anything from these guys!
Fortunately I was able to be a part of the biographical book written for all of the Merrill's Marauder's and attended several of their reunions.He was very dedicated to the Rangers (known as the original green beret' to them) and dedicated his uniform patch from the 2701 Khaki Combat Team (unit) and a Japanese flag that he had framed for the guys still remembering and serving as Army Rangers.:)
I wish you the best and also for you dad -- hopefully you will be able to find some things you can show him and talk to him about too.That sometimes helps if you know a little bit about what he was doing or what he was seeing during those days.