It's a reference to Goldilocks and the 3 Bears - the 3 bears are PAPA, MAMA, and BABY. I'm not 100% sure if you're supposed to be able to derive MAMA from the grid- but there are no Ps or Ys in the grid, which should eliminate PAPA and BABY.
But, in the story, the middle-sized chair and the middle-sized bowl/spoon and the cold porridge belong to Mama Bear. Papa Bear's porridge was too hot, Baby Bear's porridge was just right.