The best summary of Annie's life after she goes over Niagara Falls in a barrel, as described in "Queen of the Falls," is:
Annie tries many approaches to make money from her experience, but fails. She opens a souvenir stand in a park at Niagara Falls, where she sells postcards and tells her story to tourists.
This response captures the essence of her post-Niagara Falls life, highlighting her struggle to profit from her experience while also mentioning a specific action she takes in her efforts.