I would say the correct answer is B. immoral. The word impious means that you aren't showing respect to God, the respect he deserves. So when you are impious, it means you are disrespectful towards God, meaning you are acting in an immoral way, because God is the epitome of morality and everything good.
I find Helen Keller's story impressive because she demonstrates what people are capable of accomplishing. The way Helen Keller grasped words and yearned for more communication is an inspiration.