First I would check her for mites and lice (check around the vent and around the oil gland), to see if that's what's causing drowsiness. Are there any other symptoms?
From the photos, I see that she has scaly leg mites. Slather vaseline on her legs once a week for a month and you should kill the leg mites. Some people soak the legs in an epsom salt bath, then dip in thick cooking oil (to smother the mites) or motor oil (to kill the mites).
While you're treating the leg mites, just clip her nails back with human or dog nail clippers. Try to do just a little bit at a time as the quick (where the blood is in the nail) can grow with the nail. So, do a few centimeters, then come back in a few days to clip more, until they are normal chicken length again.
Good luck, she looks like a beautiful hen!