What is the ruling on marrying a young man who asks the girl to remove her khimar and replace it with a shawl that is not a hijab, with the mother's insistence on and satisfaction with this marriage, and her threat of displeasure with her daughter if she refuses?

If the suitor wishes to see his fiancée without a hijab, there is no harm in that, and she should agree. However, if he wants her to abandon the legal (Shar'i) hijab and wear something that does not cover her, she is not permitted to do so, nor should she obey her mother in this matter, for obedience is only in what is right (ma'ruf). The obligation of the legal dress should be gently explained to her mother to persuade her. If the mentioned shawl covers the entire body, including the face and hands, and is not transparent, then there is no harm in wearing it to obey her mother; otherwise, no.