Does he have the right to take possession of a house that was bought with his money that he used to send to his mother?
Undoubtedly what your father did of helping his parents and siblings and contributing to the living expenses even though he was overseas and far away from his children was an act of great kindness and a good deed.
From the question it seems that what your father did was to help the family with their living expenses, then he sent money with which this house that is the subject of the dispute was bought.
It may be said that in this case one of the following two scenarios must apply:
Either he sent this money with which the house was bought as an act of kindness to his parents and upholding ties of kinship with his siblings and helping them, voluntarily giving the money that he sent to them. In that case the house is to be included with the estate and is to be divided among all the heirs in accordance with the laws of Allah, because he gave up his wealth by way of giving a gift, so he has no right to take back his gift. And your father will be rewarded abundantly by his Lord.
Al-Bukhaari (2067) and Muslim (2557) narrated from Anas ibn Maalik (may Allah be pleased with him) that the Messenger of Allah (blessings and peace of Allah be upon him) said: “Whoever would like his rizq (provision) to be increased and his life to be extended, should uphold the ties of kinship.”
Or he was sending this money for them to take whatever they needed, and whatever was left over after spending on his family remained his property, so the house that was bought is the property of the owner of the money, because he is the one who paid its price, and his father and mother acted as deputies for him in transferring this leftover money to buy this house.
In this case it would be better if he had stated clearly to his parents or they had stated clearly to him at the time of purchase that the house was being bought in his name.
However we should advise both parties not to undermine the good relationship between them; your father should not make this a cause of spoiling the acts of kindness that he did for his family and they should not not be harsh with their brother who helped them, spent on them and treated them kindly. Is the reward of good anything but good?
And Allah knows best.