Does a single expiation or multiple expiations (for each deceased person) become obligatory upon a driver who caused the death of 23 people as a result of a car accident, and is it permissible for his wife to assist him in fasting the expiation, and is it sufficient to pay a ransom in lieu of fasting, and is blood money obligatory for each deceased person?

If a Muslim kills a soul by mistake, the blood money (diyya) is incumbent upon his 'aqila (maleagnatic relatives), and the expiation (kaffara) is binding upon him. If a group kills, expiations and blood money become binding upon them. The expiation is: freeing a believing slave; if he cannot find one, then fasting for two consecutive months. If he is unable to fast, then either the fasting remains a debt upon him until he is able to perform it (the view of Abu Hanifa and Malik, a narration from Ahmad, and a saying of Al-Shafi'i), or he moves to feeding sixty poor persons (a narration for Ahmad and a saying of Al-Shafi'i). The expiation is due from the killer's wealth alone, and it is not permissible for his wife to fast on his behalf as long as he is alive.