Annapurna is the goddess of food and grain, the form of Parvati whose name means she who is full of food, and offerings of yomari are made to her on this day.
She is the appropriate deity for a festival with no procession, no chariot and no crowd. What is being thanked is the fact of having enough, and the thanks are made in a kitchen, over a steamer, with the new harvest.
In the Kathmandu Valley she is worshipped at the Annapurna temple at Asan — the market square, which is where the valley has bought and sold grain for centuries, so the siting is not accidental. The deity there is an unusual one to look at: a silver vessel rather than a figure.
The Himalayan massif carries her name for the same reason the goddess does. Both are called full of food.
Part of Yomari Punhi