Go for agnikarma consulting the ayuevedic Surgeon
If she is not diabetic go for agni karma at a pancha karma clinic near you. Agni karma gives miraculous results for corns. Till you get one you can use corn tapes. Apply one for 3 days and then scrape the dead cells off using a nail cutter. Scrape deep till you see the first drop of blood. Corns are a collection of dead cells so there will be no pain while scraping. BUT do all of this at home only if she is NOT diabetic. Avoid wearing hard sole shoes and chappals that is a major cause of corns.