Is that Mona and Molly?
They certainly are! Lord, the art was cringe-worthy back then.
So do they meet Morris at the show or does he get a Molly's T-Shirt?
Morris says in #83 that Molly got one for him at the show and brought it over. Presumably she left before the Day 2 narrative starts... unless she didn't and she and Kerouac have been having the time of their lives reinacting Home Alone with Harry and Morris out of the house.