Is it permissible for a father to grant his house to his daughters, to the exclusion of his son, during his lifetime, if he fears that his son will force them to sell it after his death, leaving them without shelter?

The default rule is that it is not permissible to disinherit some heirs from their rightful share, and it is forbidden to use deceptive means to achieve this. Whoever does so will be treated with the opposite of their intention. If the father disinherited his son from the inheritance intentionally, then the inheritance should be divided among all heirs as Allah has commanded.

However, if the father gifted his house to his daughters during his lifetime due to their special circumstances and their need for housing, especially with the son's foolishness and lack of concern for them, then this is permissible in Islamic law. There is no sin upon the father for not treating his children equally in this case, because the general rule is the obligation of equality in gifting among children, unless there is a legitimate justification for preferring one over another.