What should I do when I experience bouts of crying over my deceased father? And what benefits the dead: reading the Quran and dedicating the reward, or supplication (Du'a)? And can I fast and pray and dedicate the reward to him? And is seeing the deceased in dreams a reality or a subconscious thought, and does the multiplicity and change of his image in the dream have an interpretation?

May Allah عز وجل console the questioner for the loss of her father. She is not at fault for not accompanying him to the hospital, as long as someone else did so. Perhaps she will be rewarded for her intention, for indeed, intention can be more profound than action. Among the ways to show filial piety to parents after their death is to supplicate for them and to perform good deeds and donate their reward to them. Seeing the deceased in a dream can be a true vision, or it can be a self-dialogue ( حديث نفس ), or a manipulation from Satan. As for weeping over the deceased, it is a mercy, but one should be careful to avoid forbidden wailing ( niyaḥah ). If the questioner remembers the loss of her father, she should console herself with the loss of the Messenger of Allah, peace be upon him, for this helps with patience. And she should strive to increase her supplications for her father instead of weeping over him.