What is the optimal course of action toward a wife who refuses to adhere to the hijab and stop watching forbidden movies, and does so in her husband's absence, especially since he lives with his brother and his children?

The husband must oblige his wife to wear the hijab and prevent her from watching unlawful things, because he has the right of guardianship over her, and he is responsible for her before Allah. It is not permissible for the husband to let his wife commit evil if he can prevent her. Furthermore, it is not permissible for the wife to live with the husband's brother in the same dwelling if it leads to unlawful seclusion (khalwa) or prohibited mixing. The wife also has the right to an independent dwelling. The husband is advised to teach his wife matters of Islamic law, help her adhere to obedience to Allah, recite the Qur'an, and frequently supplicate.