So sorry for your loss. No one should have to experience the loss of of a parent at such a young age.
Don't give up. If children have had a good foundation in the gospel at home, they often come back to principles and values with which they were raised when they are older and more experienced in life.
Train up a child in the way he should go: and when he is old, he will not depart from it. (Proverbs 22:6)
Mold a child when he is young, and he will be sure to mold when he is old. (Proverbs 32: 1)
They're still young, not yet old ... I'm claiming THAT element.
I’m glad the Prodigal Son story is in the Bible!