How can I deal with the severe psychological shock resulting from my mother's sudden death, while maintaining my faith in God's decree, and how can I honor her after her passing?

We advise contentment with Allah's decree and submission to His judgment, knowing that what has befallen you was not meant to miss you. As for honoring one's mother after her death, it is by making abundant supplications for her, showing mercy to her, and seeking forgiveness for her. Every act of devotion whose reward is dedicated to her will benefit her, Allah willing.