Pinworms are transmitted by poop. The females lay eggs inside the digestive tract, and they are pooped out, and then if another animal ingests it, they become infected. Crickets left in the viv can also eat the poop and then pass on the worms.
They are relatively easy to kill though, regular bleach will do it.
I'd take everything out of the viv and give it a good clean in a bleach solution. Anything wooden I'd clean and then bake in the oven to ensure it was fully sterilised, and then I'd only put non-porous furniture back in the viv until she was better.
I'd
bathe the beardie every day, partly because meds can lead to dehydration, and most importantly to try and get her to poop in the
bath and not in the viv...much easier cleanup! If she does go in the viv, clean it immediately. Make sure no crickets are ever left in the viv for more than 10 minutes.
Your other dragons shouldn't catch them off her (assuming they are housed separately) provided you wash your hands between handling and obviously don't take live food out of her viv and put it in theirs...and it's always a good idea to handle healthy animals first and then move on to the sick one last.
As far as parasites go, pinworms are pretty easy to deal with...just keep everything clean and poop-free, and the chance she'll get reinfected or infect one of the others is very small.
If you want to stop her getting them ever ever again, then you might want to start your own dubia colony. I believe they don't carry pinworms...most of the time beardies get them from crickets.