Is the possession of a house, land, and half of the furniture from the aunt during her lifetime and without a will considered a deprivation of the heirs?

If the gift (hiba) was completed while you were legally competent to act, and it fulfilled its conditions—namely, the giver relinquishing possession of it and your taking possession of it—then it is Islamically valid. You own what was gifted to you, even if it was all the money, because the owner has the right to dispose of their own property. There is no difference whether the source of the money was from the inheritance of a father, a husband, or anyone else; the aforementioned gift is valid.