Symbolism, Imagery, Allegory
Fire appears throughout the novel and results in the deaths of Hannah and Plum. There are many possible meanings of fire, one of which is the idea that it is cleansing. When Eva douses Plum in kerosene (before the fire, but still applicable we think), he feels like he's undergoing "Some kind of baptism, some kind of blessing" (1921.49). And when Hannah dies in a fire, it's possible that this somehow cleanses Sula of a mother who is at best indifferent and at worst admits to not liking her daughter.