What is the ruling on the prayer and fasting of a woman who became pure from postpartum bleeding (nifas) before forty days, then the bleeding returned to her? And must she also make up the days she fasted?

The maximum duration of postpartum bleeding (nifas (definition)) is forty days, and there is no minimum duration. If a woman experiencing postpartum bleeding sees purity before forty days, she should perform ghusl (definition) (ritual purification), pray, and fast, and her fast is valid. If the blood returns within the forty days, she reverts to the state of nifas, and must cease praying and fasting. The six days your mother fasted are valid, and she is not required to make them up; she should make up the days she missed thereafter.