Do you have pictures or descriptions of the blooms? If not, play it safe this year and do not prune at all, except to remove stems that do not leaf out by the end of May or early June. Hydrangeas do not normally need to be pruned so you will be fine. Deadheading of spent blooms can be done at any time of your choosing.

She acrually does know what they are— limelight hydrangeas.

Pruning now will not be harmful nor will it affect Limelight’s blooming in the summer/fall.

There is nothing to prune on those plants except dead material, which wouldn’t bloom anyway. If you bend a twig and it snaps it’s dead. If it just bends it’s usually still alive.

Limelights are hardy if they get 6 hours or more of sun and regular watering so she can leave them alone. If she wants to help them, she should cut off (prune) the branches that are narrower than a pencil. They are weak and won't be able to hold up the huge flowers. There are lots of those the Limelight in the second photo.