。
She was a woman living from day to day.
Literal
She [topic-は] that-day-living [genitive-の] woman was.
その日暮らし ('living for that day') is the Japanese equivalent of 'hand-to-mouth' — getting by from one day to the next without surplus or savings. Here it attaches attributively with の to modify 女 ('woman'). The compact structure ~の女だった ('was a [X-modified] woman') is a small but useful adnominal pattern: a noun phrase rendered in modifier form to describe what kind of person someone was. Slightly literary, the kind of summary line you might find in fiction or a biography. Depending on tone and context, the phrase carries either pity or admiration — poverty's grim shape, or a free-spirited refusal to plan.