Just outside, give the rice pouch to her son. He will process it into Sweet Rice.
Take the rice back to the Grandma. She will reward you with one of the following:
3 Hearty Rice Cake
2 Lucky Rice Cake
2 Honey Pastry
2 Sesame Pastry
3 Salty Rice Cake
3 Plain Rice Cake
2 Rainbow Cake
2 Korean Rice Cake (Weighs 1, Description error)
1 Green Maiden Pet Egg (Given along with one of the other items)
1 Red Envelope (Given along with one of the other items after the player has received the Egg)
Green Maiden
Food Mojji can be found in payon (126,113). 10 Mojii for 3,000 Zeny. The NPC will only sell Mojji to characters who have received an Egg from the Grandma.
Note: The Green Maiden Pet Egg can only be awarded once per character.