Answer:
Breakfast, dinner, and supper were very silent meals—for Anne still remained obdurate
Explanation:
The sentence that suggests that Matthew and Marilla missed Anne's chatter when she stayed in her room in the sentence above because meal times were described as being very silent because Anne was still obdurate.
From the excerpt, it is clear that Anne had done something wrong and she was being asked to apologise to Mrs Lynde but she refused and because of that she was made to stay in her room.
The phrase "for the new committee" is a phrase that starts with a conjunction. It is also known as a subordinate clause. The combination of words "for the new committee" does not make up a complete sentence; it cannot stand on its own. The word "for" is a coordinating conjunction and joins two equal phrases to each other. A coordinating conjunction is also known as a coordinator. It shows that both parts or phrases that make up the sentence are of equal importance.
It looks to be both A and B but if you can only choose one I would go with B. Hope I helped!