If you watch the Strand movie they talk about the project that this picture was a part of. All of these brothers served in the Italian resistance during WWII. The father was killed I think. They are all surrounding their mother whose positioning in the doorway and the darkness serves to link her to each of them compositionally. Great picture. Strand's wife talks about how horribly unpicturesque the town was. He and the Italian that he was working with (director of the Bicycle Thief I think) decided on this village by randomly sitcking pins in a map. This town was the third they hit, and happened to be the hometown of the director.
In Paul Strand / Cesare Zavattini's book : "UN PAESE - Portrait of an Italian Village", Aperture, one not only finds this photo ( plus many others). It is also accompanied by the mother's statement that provides additional iconographic background.
A great book revealing the strength and dignity of humble people (- if that's the wright word).