Who is Zerelda James from The Assassination of Jesse James by the Coward Robert Ford and what is their importance?

Jesse and Frank's mother, she is a very large woman who is vocal about her displeasure in Jesse's choice of a career because it puts his life in jeopardy. She often berates him for bring misery on his family. She loses a hand and her son when the Pinkerton detectives throw a bomb into her house. She charges for those who want to see the house where Jesse lived and makes some money from the tourists.