The last muffin on 24 is on a house roof below Derpy, and for level 22-
Muffin #1- Near the Top of the Castle in the middle
Muffin #2- In front of a blue-ish/green pegasus behind the royal gaurds
Muffin #3- Near a bush on the right side of the scream
I posted this on your profile, just to not give hints to the others still playing the game