Yep, that’s bumblefoot! My recommendation would be to soak in epsom salt water for 10 minutes, and then remove the scab. It may be necessary to loosen it with a sanitized razor blade. The infection, a white/yellow ‘kernel’, should come out with the scab. If it doesn’t, try squeezing the footpad, or use tweezers to try and remove it. I’d recommend you have someone to hold her still while you work.
Then, flush with Veterycin/Saline/diluted Hydrogen Peroxide, and pack the wound with plain neosporin.
I like to use Vetwrap to bandage it. Here is a helpful article:
https://www.backyardchickens.com/articles/how-to-correctly-wrap-a-chickens-foot.77028/
I would change the bandage every 2-3 days.