The Epsom salt will help with healing inflammation and swelling. Has the infection left out of the ankle area? She might benefit from an antibiotic to make sure there isn’t anything left.
https://www.backyardchickens.com/threads/another-bumblefoot-post.1492463/#post-24896429
Are you soaking your ducks foot in Epsom salt water along with the other things your doing? Was the infection localized? in other words no swelling or infection other than where the bumble was?