What is the ruling regarding a mother who does not provide for her daughter and deliberately provokes her, knowing that her daughter suffers from excessive nervousness and takes sedatives, even though the daughter asks for nothing but peace and tranquility?

If the daughter possesses sufficient means for her own sustenance, then the mother is not obligated to spend on her. The daughter is advised to fear Allah concerning her mother, for the mother's right is immense, and Allah's pleasure is from her pleasure. Indeed, Allah has coupled His right with the right of parents. She must beware of disobeying her mother or incurring her displeasure. She should endure any actions that may emanate from her, and advise her mother with gentleness and leniency. She should strive to refrain from shouting at her and seek Allah's forgiveness for anything that may have transpired from her.