Hi! As stated above, if the father's property is self-acquired, that is, it's been purchased by him during the lifetime of his heirs, using his own funds and without detriment to the joint family property, he can dispose of such property as he pleases.
However, if it's joint family property that you speak of, he can make a gift of the share over which he'd have exclusive ownership; i.e. only his share of the ancestral property. He can also alienate the said property in the favor of his brother if both you and your mother consent (assuming you two are the only remaining family members.)