Is changing the prices of books and tuition fees in order to get money from parents considered lying, and is the money taken in this way unlawful (haram), and how can one atone for that?

The fundamental principle is that lying is forbidden. However, if you need to lie to obtain money that your father has permitted, and you cannot use dissimulation (tawriya) or ambiguous statements (ma'arid), and telling your mother the truth would cause her extreme anger and significant distress, then you are permitted to lie in this situation to obtain the money and maintain your mother's satisfaction. Therefore, if you lied about the prices of books and expenses because you were compelled to, and there was no other way to obtain the permitted money while satisfying your mother, then this is considered permissible lying. Otherwise, it remains fundamentally forbidden. The money taken is not unlawful as long as it falls within what your father permitted. It is advisable to strive for honesty in the future.