Is what the brother did, pouring methylated spirits on the coal, which led to the mother's death, considered accidental killing, and does the brother inherit from his mother in this case?

Pouring alcohol on charcoal to speed up grilling, if it does not result in significant harm, does not incur liability nor is it considered accidental killing. However, if it usually causes such an out-of-control ignition, then death resulting from it is considered accidental killing, and the one who caused it is liable for what resulted from it. In the case of accidental killing, blood money (Diyya) and expiation (fasting for two consecutive months) are obligatory. The Diyya is to be paid by the killer's 'Aqila (male agnates). Scholars differ regarding the inheritance of the killer: the majority forbid the killer from inheriting absolutely (whether intentionally or accidentally), while the Malikis hold that the killer does not inherit from the Diyya but inherits from other wealth.