Are acts of obedience (such as supplicating in prostration, performing Qiyam al-Layl, and reciting Surat Al-Baqarah) to be reduced for the sake of sitting with family? And is playing cards (kotsina) haram?

You must strive for balance and approximation in your dealings with your family, adhere to your obedience, and try not to anger your mother. Apologize to her gently and kindly, and explain to her your preoccupation with prayer. If your mother becomes angry, reduce your supererogatory (nafl) prayers to the extent that her anger is appeased.