What is required for me to get guardianship over my grandaughter whose mother ped away?

My daughter died two weeks ago. She was married, but her husband is not the father of my granddaughter. Her father is in another state. Her father, stepfather, myself, and my granddaughter all want me to have guardianship over her. I am trying to find out what doents I need and where to go in order to do this. Any help would be greatly appreciated. We are in California.