Is expiation for an oath incumbent upon my mother who swore by Allah that I would not bring the car to the South, and then I bought it and brought it?

What was uttered by the mother is not an oath, but rather a question asked by Allah, and scholars have permitted asking by Allah, as in the Hadith: "Whoever asks you by Allah, then give him." There is nothing upon the mother, because this is a question and not an oath, and there is no expiation for whoever does not answer the question.