What a shock, and so unfair to your daughter. Guilt, even when unwarrented, is very hard to shake. If you have a spiritual or other community, let them help with the grief and healing. Few people are any good at gracefully supporting a grieving person so please be graceful yourself with their awkward attempts. If somebody says "Call me if you need anything", then call them when you do. God bless you both and may peace be with you.