Who is Marya Nikolayevna from The Endless Steppe; Growing Up in Siberia and what is their importance?

Marya is a very wealthy woman, whose husband is a high ranking officer in the army. She asks Esther to make her a sweater out of a torn, dirty skirt. Esther agrees to make the sweater, but over time, Marya gains quite a bit of weight and the sweater does not fit.