explain purpose of mrs ross re-appearence in the novel at the end of part 3

Through Mrs. Ross's reappearance, the reader can see the effects on civilians as the war progresses. She is emotionally spent and takes to going out in storms, dragging poor Ms. Davenport with her. She catalogs Robert's letters and writes back to him in indecipherable handwriting. The distance from her son has had a lasting effect on her. Her desire to venture out in terrible weather betrays a need to be close to what she feels her son must be experiencing. She cannot know warfare firsthand so she puts herself in the worst conditions she can find. Some scholars see this not solely as madness but a desperation on Mrs. Ross's part to keep her bond to her son as strong as she can. By trying to know what he is experiencing, she feels that he is alive in her, echoing the sentiment Rodwell expressed in the letter to his daughter.

The distance between Mr. Ross and Mrs. Ross appears to have only grown, though he still loves her. She reveals that being loved is the greatest burden in her opinion. This once again echoes the theme of private vs. public. Being loved requires one invite another into one's private life. Mrs. Ross is uncomfortable with this idea as it also means she has to know the intimate parts of others' lives.