Is it permissible to secretly marry a young man whom the mother rejects due to her hatred of his father and her belief that the marriage will bring a curse, even though the father approves and the Imam supports the young man?

Firstly: No one is permitted to perform istikharah (prayer for guidance) on behalf of another. Istikharah must be performed by the person who has the need himself. Whoever performed istikharah for your mother has fallen into innovation (bid'ah) and has caused you harm.

Secondly: If a mother refuses her daughter's marriage without a valid reason, there is no sin upon the daughter if she marries with the consent of her guardian (wali) (her father). She does not commit a sin by doing so. Obedience to parents is obligatory in matters that benefit them and do not harm the child. However, obedience to them is not obligatory if the matter entails harm to the child or does not benefit the parents. Therefore, you are not obligated to obey your mother in abandoning this marriage, as it contains benefit for you and harm for you in complying with her.

Thirdly: Marrying secretly from the entire family is incorrect due to the absence of the wali, who is a condition for the validity of the marriage contract, and it also brings problems. As for marrying secretly from the mother only, with the knowledge and consent of the father (the wali), it is valid. To determine what is best, one must weigh the benefits against the harms. If it is possible to dispense with the young man and prioritize the mother's satisfaction, that is better. Otherwise, marrying him is better, while striving to appease the mother and prioritizing family cohesion over personal desire if possible. One should seek help from Allah, supplicate, and perform istikharah before making a decision.