Should the father be informed that the mother has taken out usurious loans without his knowledge, considering that the mother has repented and the father is strict and might divorce her, and she is unemployed?

Borrowing with interest (riba) is forbidden, as it involves assisting in its consumption, based on the Almighty's saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." The Messenger of Allah, peace and blessings be upon him, cursed the one who consumes riba, the one who feeds it, its scribe, and its two witnesses. You have done well by advising your mother, and her concealment is required, especially after her repentance. Do not inform your father about the matter as it could lead to corruption. Instead, try to help her and ask your father to assist her without detailing the reason for the debt to him.