I am so very sorry for your loss. We lose a little piece of ourselves when we lose a parent. Part of what you are feeling right now is grief. For whatever reason part of the grieving involves guilt. We feel guilt because we did _____or we didn't do_____ or we "let" _______ happen. It takes a long time to work through it.
I lost my Dad two and half years ago in a small aircraft accident (he was piloting). I felt guilty because I was supportive of him buying the plane. I wanted the NTSB or FAA to tell us specifically what caused the crash. I wanted answers. They never concluded what happened. Pilot error? Mechanical failure? We don't know. I still have nightmares about the violent and sudden nature of his death and the discussion I had to have with the coroner.
What I learned through this difficult period of grief is that I did not cause his death and I could not have prevented it. You didn't cause your mother's death. You couldn't have prevented it. Sometimes things happen and we don't get to know why. I wish I could give you a hug--I understand how your heart must hurt right now.
gentle hugs
ke