Surprise!
Right when I thought the Date with Dad event ended in 1979, I just so happened to flip to a random page in the 1989 Quair and found this:
I was shocked to find that the event was still happening ten years later, and it took me a very long time to realize that it was still occurring in 2007...the last year of Douglass College. While I did not find any record exactly saying so, I assume it disbanded after that year, much like how the Quairs themselves were discontinued.