What a kind compassionate man, to have made sure he could ease your worries after having been in surgery!
I'm sorry that I don't have much in the way of a suggestion for a "Thank-you' gift. The only physician-related thing that pops to mind are the pictures Norman Rockwell did! I'm sure he would appreciate a nice warm quilt to wrap up in and catch some Zzzz's when he has a break during a long shift!
Prayers for a Happy & Healthy New Year for your DH and you!