I am so so sorry for your loss. I cannot imagine the heartache which you and your daughter have endured. I can, actually imagine it, having grown up with alcoholic parents, but I did not have the close and loving aspect, and did not lose them as a young teen.
Please, get some help for your daughter. It sounds like she has suffered anxiety over this for a long, long time. That sort of anxiety does not simply go away, it affects how we feel for our whole lives.
This trauma which she has suffered needs addressed, and I hope that she will find peace, and counsel would help her in that, I think.
He is not suffering now, and that has to be a blessing. Wishing you peace, and comfort .
chicory