Here's my idea for Yet Another Monster at the end of this book: Starring Lovable Furry Old Grover, Lovable Furry Little Elmo and featuring Lovable Furry Cookie Monster
The Cookie Monster is on the fence on the issue of the Monster at the end of the book, but Elmo suggests that the Monster might have Cookies. A giant vicious-looking monster (much like Frazzle) is at the end of the book, a terrified Grover and Elmo scream, then run away. Cookie stays behind and asks the new monster if he has any cookies, the monster replies "Oatmeal Raisin" The final scene is Cookie Monster happily eating cookies with his new friend