It's best to give wormers orally, that way you know they were properly wormed with no guesswork. Pre-load your syringe with 1/2cc Valbazen. Have someone hold the hen for you. Pull the hens wattles down with fingers and thumb, her mouth will open. Then shoot the wormer in her open mouth and immediately let go of the wattles so she can swallow the liquid on her own.
If you dont immediately let go of the wattles, the liquid may go down her windpipe, then there would be big trouble.
If she shakes her head, hang on, she will tire out, then administer the wormer. Make sure you release her wattles, I cant emphasize that enough.
Reworm your birds again in 10 days.