What is the Sharia ruling on the marriage of a young man and a young woman when the young woman's family has agreed to it, except for her mother who refuses without a reason, knowing that the young man and the young woman are devoted to each other?

We advise the questioner to strive in convincing her mother to accept the young man. If the mother insists on refusal, the daughter is not obligated to obey her if the young man is suitable. The daughter must be dutiful to her mother, and it is not permissible for her to mistreat or boycott her. Guardianship in marriage belongs to the male agnates (ʻaṣabāt), and the most rightful persons to give a woman in marriage are her father, then her grandfather, then her son, then her brothers. The relationship between a non-mahram man and woman, whether through correspondence or otherwise, must be severed until marriage takes place.