The excerpt that best shows Mrs. Peters caught between her role as the wife of a law enforcement officer and her empathy for lonely, isolated women is B. "I know what stillness is," repeated Mrs. Peters, in just that same way. Then she too pulled back. "The law has got to punish crime, Mrs. Hale," she said in her tight little way.
It's the second time she says "I know what stillness is", the first time she starts to tell he story about her dead toddler and gets interrupted. She understands the pain Mrs Hale must be suffering, but the law must be enacted anyway.