Final answer:
The mother is worried about the cat because it never came home after church. Sylvia expresses her desire to live on the farm and not return home, leading the mother to worry that the cat may not come back either.
Step-by-step explanation:
The mother is worried about the cat because A) the cat never came home after church. In the story, Sylvia whispers that the farm is a beautiful place to live and she never wants to go home, so her mother worries that the cat may never return. This suggests that the cat may have found a new home in the farm and may no longer want to come back. Therefore, the mother is concerned about the cat's well-being and whether it will come back.