What must I do to pay the blood money for accidental killing on behalf of my father, who believed he caused the death of a person in a car accident but was not certain, and he died before paying the blood money?

If a driver takes all necessary safety precautions, adheres to traffic rules, and maintains full concentration, then what happens thereafter that they could not avoid, they are not held accountable for it, and there is no expiation (kaffarah) or blood money (diyah) upon them. However, if any of these conditions are not met, then they are held responsible for what occurred, and expiation becomes obligatory upon them (freeing a slave or fasting for two consecutive months), and their 'aqilah (male relatives on the father's side) are obligated to pay the blood money if it is certain or highly probable that a person died. But if the matter is merely doubt or illusion, then nothing is required of them. The blood money is for the heirs of the deceased, or it may be placed into general Muslim public welfare.