Fatima is a woman of the desert. Did she live in a house or something else like a tent?
Paulo Coelho does not specifically describe Fatima's home. Since she does live in the desert, and since there are not many building materials there, one can probably assume that she lives in some sort of tent-like structure. It's not so important to know for sure exactly what sort of structure she lives in as opposed to focusing on her character. Paulo Coelho wants us to always remember the fact that Fatima is a "woman of the desert", and she will "wait with hope" for her man's return.