The Grandmother's Gift is a Quest item obtained after agreeing to do a favor for a grandmother in Kaocho, who asks you to deliver it to her granddaughter somewhere in the Sana region. The actual location of her granddaughter is at Tonfon, which will not be accessible until late in the game. When delivered, the granddaughter will accept it and later give you the Granddaughter's Gift.
Due to the Grave Eclipse, most of the citizens in Kaocho die by the time the player can reach Tonfon. Because of this, the player must acquire the Grandmother's Gift before entering the Clouds of Passaj if they want to complete this sidequest.