Grab

Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 1) bludgeoning damage. If the target is a Medium or smaller creature it is grappled (escape DC 11). Until the grapple ends the zombie can't grab another target.

Bite

Melee Weapon Attack: +3 to hit, reach 5 ft., one grappled target. Hit: 6 (1d10 + 1) piercing damage and the zombie regains the same number of hit points.