What is the ruling on the money the questioner took from his mother, and the money the mother took from him, given that the money was a gift from the grandfather to the questioner and his two brothers, and the mother took the share of the questioner's younger brother because he was young?

The money allocated to the questioner from his grandfather's gift is his property, and there is no harm in taking it, whether after giving the mother the remaining amount or after handing her the full amount. As for the money of the young, underage brother, the mother may take from it if she is in need, according to the hadith (definition): "You and your wealth belong to your father." The mother is like the father in this regard, and she is permitted to dispose of it for the benefit of her child, especially if the money is little.