Will the husband be held accountable for his wife's death as a result of falling asleep while driving and his negligence, and what is his punishment?

There is no sin upon the man who accidentally caused his wife's death while he was asleep during travel, because he was asleep and made a mistake, and the pen has been lifted from the sleeper and the mistaken. He is obliged to offer expiation (freeing a slave, or fasting for two months if he cannot find one), and his 'aqilah (male relatives on his father's side) are obliged to pay the mitigated blood money (diyyah). It is advised to treat the son-in-law well and not accuse him, as he is afflicted just like the wife's family, and cooperation with him in raising the children and maintaining a good relationship is necessary.