Would the reward of the brother who contributed a larger amount to his mother's Hajj expenses, while not sending her money monthly, be greater than the reward of the son who sends money monthly and contributed a smaller amount?

If the brother contributed a larger amount to the expenses of his mother's Hajj, then his share of the reward for assistance is greater, because the reward is proportionate to the amount of expenditure and effort. However, the questioner's monthly financial assistance to her mother grants her immense favor and reward, surpassing her brother in this aspect.