It's likely the ants were attracted to the scent of the birthing fluid. If that smell is cleaned out of the nest and the kits have been cleaned off by the mom and you, that should stop the ants from being attracted to the area. But I'd regularly check on the kits today and the next few days, to be sure.
If there's still a risk or you're concerned, spraying around the cage with a water/dawn dish soap mix may stop the ants. Or a rabbit safe pesticide may be needed. Or bringing the nest box in the house and just taking it back out in the morning and evening for mom to nurse may be another option, if this won't cause issues with your doe.
