Is it permissible for the father and his brothers to sign over to his son the father's share of an old house that the son renovated into two floors, one for his parents and the other for himself, and what is the share of the sisters in this case?

A father must be just among his children in giving gifts, and it is not permissible for him to favor one of them with a gift without a legitimate reason, for the Prophet, peace and blessings be upon him, said: "Fear Allah and be just among your children."

So, if your father singled you out with the gift of the old house without justification, he has committed something forbidden and must repent and rectify his unjust gift by giving your sisters a similar amount or its equivalent if possible. If he cannot, then nothing is incumbent upon him. However, if he gave you the house in exchange for your building a floor for him, this is a matter of compensation and not a gift. In both cases, the house is yours, and your sisters have no share in it unless you donate to them.