Is it permissible for a mother to transfer a plot of land to her son, and is it permissible for her to give him money in compensation for what she spent on his siblings, given that some of the money the son sent to her was for savings, awaiting its return, and other amounts were not expected to be returned?

You are not permitted to reclaim the money you sent to your mother for her personal expenses, whether it was a gift or a mandatory maintenance payment from you.

Your mother is not allowed to favor you with a gift, such as registering the land in your name; she must be fair among her children.

If your mother spent money on your two brothers, and their maintenance was obligatory upon you, then you are not entitled to reclaim it. However, if their maintenance was not obligatory upon you, and your mother spent it on them without your permission, then you are entitled to reclaim it, and there is no sin upon you in taking it if your mother wishes to return it.

If you have a right to the money and you both agree that your mother will give you something else in exchange for it, there is no problem, unless the value of the compensation is substantial, in which case it appears to be a preferential gift.

A mother, like a father, must be fair among her children in giving gifts.

A child is permitted to demand his money from his father if the father is wealthy and the child is in need, but if he refrains from demanding it, he will be rewarded for that.