Is the questioner considered a murderer of his wife and daughter, and what are the implications in this matter and his status regarding inheritance, after they were exposed to an accident that led to their death?

If the driver was driving at a reasonable speed and could not avoid the pothole, then nothing is incumbent upon him. However, if he was driving at an excessive speed that made it impossible to control the car, then he is liable for diyah (blood money) and kaffarah (expiation) for each deceased person due to his error, because the negligence lies in the excessive speed or in not ensuring the car's roadworthiness. If negligence is found, then diyah and kaffarah are incumbent upon him. The diyah is waived if the heirs relinquish it, unless the deceased had debts or minor heirs. The expiation for accidental killing is the freeing of a believing slave; if one is not found, then fasting for two consecutive months.