The hawk population will drop while the rabbit population will rise.
Explanation:
With the way the pyramid is structured, it shows that the rabbits eat grass, snakes eat the rabbits, and hawks eat the snakes. If the snakes are gone, the hawks will lose a food source, and their population will drop. Also, the rabbit population will rise, because the snakes eat the rabbits, and if the snakes are gone, they won't have any predators.