Any mentions of Mr. Hooper after he died?

[GonzoLeaper]

I'm sorry. I still don't recall that. Are you sure you're not thinking of "Stars and Stripes Forever: A 25th Anniversary Celebration?" I remember that one showed flashbacks of Hooper but it wasn't a Christmas special.​

In like 2011 or 12, there was this thing on pbs. It was like a Christmas Eve thing, and there was some flashbacks of him. I'm not sure what if was called. I only saw it once.

Are you maybe thinking of "A Sesame Street Christmas Carol"? That's a 2006 direct-to-video special that did indeed feature an appearance by Mr. Hooper (obviously in archival footage- it was clips with him and Ernie and Bert from "Christmas Eve on Sesame Street") - since Oscar the Grouch was being treated to reminders of Christmases past (since he was playing the role of Scrooge in the video). I'm pretty sure it has run on PBS at Christmas time before.
http://muppet.wikia.com/wiki/A_Sesame_Street_Christmas_Carol