Is money earned by a father from a company that deals with usurious banks considered unlawful, and what should be done about it?

If your father does not directly engage in usurious transactions nor assists in them, and the majority of the company's funds are lawful, then there is no objection to working for them, although it is preferable to avoid it to steer clear of doubtful matters. However, if the majority of the company's funds are unlawful, then working there is considered detestable (makrooh) by the majority of scholars. But if the father participates in carrying out usurious transactions or performs them himself, then it is not permissible for him to work and he must abandon it and repent. As for you, if your father's work is prohibited and you are unable to earn a living, then it is permissible for you to take from his money only what is sufficient for your needs without excess, because you are in the position of one in dire necessity.