Audio problem: When Lynette warns Anne to never lay a finger on her son Porter again, from behind Lynette's head she is still talking, but no words are coming out.
Audio problem: When Lynette slaps Anne Schilling across the face in the wash room, a slapping sound can be heard after her hand goes past Anne's face.
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.