On pp 67 we meet david's grandmother. How is she different from the other women in the novel, especially David's own mother? Why is this important?

Grandma Hayden is a frail old woman who has an unknown heart condition. She is rather submissive. She leaves the room when upsetting topics are discussed. David's mother is much more assertive and demands to be a part of serious discussions. She has her own opinions about things and is not afraid to make her displeasure known to her husband.