Is there a remedy that helps heal a pressure ulcer on the back of a heel?

Yes. The key is establishing a correct diagnosis. You should find a wound care center where specialists can evaluate your ulcer and develop a comprehensive treatment plan.
Heel pressure ulcer. You need to work with your wound care team to relieve the pressure off of the heel: that is the most important thing that you can do. Without that relief, it really does not matter what product you put on the wound itself. Your wound team needs to take a look at the wound and help decide what is best for you.
Yes. However this is a very complex problem that needs aggressive attention. There is no one remedy but as long as there is no gangrene or infection and sufficient blood flow, pressure relief and good nutrition the wound should heal. Please seek the opinion of a vascular surgeon to help you through this.