ANSWER:

People who die on kufr or shirk will never be forgiven and it is not permissible for their muslim children to ask Allah for forgiveness.

QUESTION: I wanted to know if the people who commit sins all their life like doing black magic and going to dargahs, if they die a painful death like cancer and their children are praying for their maghfirat like doing charities n all n praying for em, will their sins be forgiven by Allah since they died of cancer and their children praying for em