Is it better to hold a non-Islamic wedding at a high cost to fulfill the mother's wish, or to save the money to perform Umrah with the wife, knowing that the family will not agree and the mother will be very angry?

Obeying and honoring one's mother is a great and obligatory duty, but it is not permissible to obey her in matters that displease Allah, for there is no obedience to a creature in disobedience to the Creator. Therefore, it is not permissible to hold a wedding ceremony that includes violations of Islamic law, even if you fear your mother's anger, because there is no comparison between Umrah as an act of obedience and a party like this as an act of disobedience. The ruling of the Sharia should be explained to the mother gently and politely, and one can seek help from relatives or religious people whom she respects. There is no objection to holding a ceremony that brings her joy without violating Islamic law.