Bayonet wounds (or any caused by hand-to-hand combat) have been so rare for the last 100 years that I'm surprised your father did not receive a Purple Heart.
As other posters have mentioned, you may be able to remedy this by getting a belated Purple Heart awarded, especially since the type wound and the action in which it must've occurred was so rare.
What medical histories are you basing your claim that bayonet wounds have been so rare since 1903? If my member serves me correctly, our troops were engaged in two world wars and the (ongoing) Korean Conflict over that time. While the percentage of such wounds is low compared to shrapnel wounds from artillery or bullet wounds, bayonet wounds were not particularly rare in those three wars.
You are apparently also unaware of how records were kept in the days B.C. (before computers). World War II veterans have recently received medals they should have received 60 years ago. If you have a major military installation near you, call the Public Affairs office and ask if there have been any World War II veterans who have finally had their medals catch up with them. Or you can simply look for such stories on line. Such awards are still fairly common here. (In Massachusetts. That's probably because the First Infantry Division was stationed at Fort Devens but spent from February 1942 through August 1945 on a world tour of North Africa, Sicily, Italy, Normandy, northern France and central Germany.)
I would write more on this subject, but I have to attend a funeral for a member of the Big Red One who died Saturday at age 83.