Put a generous amount of vaseline on the legs daily or better yet twice a day for 3 weeks. All chickens she's been in contact with also need to be treated. Dust the chickens 2 times 10 days apart or use eprinex 10 days apart. Clean out the entire coop from top to bottom - scrub everything. Throw away the perches and replace. Either dust or spray the coop with permethrin based product.
This was the only way I completely got rid of the mites with the group of rescue chickens I had. Don't assume they are gone just because the feet look better - it doesn't take long for them to look better but the mites are still there. The reason I say to dust or use eprinex on the chickens is not completely for the leg mites - from my experience, most chickens that have leg mites also have body mites and/or lice.
Good luck. I know it's a lot of work, but it's best to do it right the first time.