A.
If you want people to know that your father-in-law is retired,
you would say "Col. James Brown, USAF Retired, and Mrs. Brown.
It really isn't necessary to specify that he is retired unless
you want to, since the title is his for life. My husband is
also retired military. At the time of our son's wedding, to the
daughter of an active duty officer, the invitation simply said
Col. and Mrs. Smith and Col. and Mrs. Tooman. It is up to you
which wording your prefer.
Glenna Tooman, ForeverWed.com
Wedding Consultant