How is the money saved by the questioner from her grandmother to be distributed after her death, knowing that the grandmother willed it to be divided among her three children, two of whom have passed away?

This money belongs to your grandmother, and she can dispose of it during her lifetime. If she does not, then after her death, it transfers to her surviving son, and her grandchildren have no share except through a will that does not exceed one-third of the wealth. This is because the heir is the one who is alive at the time of the deceased's death. If the grandmother dies without a will, all her money goes to her son.