Color and Light (a.k.a. I Must Be Dreaming) - S2-E7
Visible crew/equipment: Right at the beginning of the episode, we see a woman drop her daughter off at a strangers house. When the front door opens, a camera crew is reflected in the brass door knocker.
Answer: Kayla was sent away in episode 16 (The Gun Song) in season 4, after falsely accusing Lynette of child abuse. She now lives with her grandparents - probably Nora's parents.
I'm curious why we never see her again, why she never talked about, and why Tom never mentions visiting her.