Is the mother responsible for the death of her daughter, whom she breastfed butter due to not having milk, while fearing that the butter was the cause of death and being unaware of that?

The legal ruling depends on consulting specialized doctors. If they state that feeding butter to a newborn leads to death, then the mother has accidentally killed her infant, and she is liable for blood money (Diyyah) and expiation (Kaffarah).

The blood money is to be paid by the killer's 'Aqilah (male relatives on the father's side), and the expiation is the freeing of a believing slave; if that is not found, then fasting for two consecutive months.

However, if they state that this does not lead to death, or if they are unsure, then there is nothing upon the mother.

The blood money for an accidentally killed female infant is half the blood money for a male, and it is paid to her heirs.