It's instinct for us to want to know, but speculation is never going to get us there - I have seen many different times mentioned on the internet over the last few hours. I do think it is likely that Charles and Anne were there but by the time the others arrived she had gone - Sophie Wessex's face said a lot. That is purely my speculation.
Unfortunately, at the age of 96, every day is a bonus. My grandmother is 96 with numerous health issues and we are all acutely aware that every slight fall could be the end (not, of course, that this stops her hopping round her house without her bloody stick - her choice).
When my grandfather died (her husband of 71 years), he had been healthy apart from his vascular dementia. He suddenly became ill and we were informed that should we wish to, we ought to see him asap. I believe he was ready to go and had decided it was time. The last time I saw him he was OK, but frail. As I left, he gripped my hand and stretched for a kiss and said "Goodbye BM". The look in his eyes told me it was the final goodbye. He went a couple of days later - I did not go back since we had already taken our leave of each other. It was just right. I am glad that his darling daughter and his beloved wife were with him at the end.
The problem is with this type of thing is that the best person to be able to tell you what was known and what was heard and felt is the deceased. All those who remain can do is hope that the passing was as their loved one wanted or take solace in the fact that their loved one is at peace.