To marry a woman from the People of the Scriptures
some young men bring Christian girls to conclude marriage contracts to them while they have no Waliy (a legally accountable person acting for a woman regarding marriage).
The girl may be accompanied by her mother, but there is no father or male relative. The girls are virgins. Is their marriage contract valid without a Waliy? Is the mother considered as a Waliy?
It is not permissible for a Muslim man to marry a Christian woman unless she is a chaste woman who has not committed adultery/fornication. Her father should assume the concluding of the marriage contract as a Waliy and if she has no father then any of her close male blood relatives should assume it. The Prophet (peace be upon him) said,
There is no marriage without the permission of a guardian.
If she does not have a Waliy, the Mufty of the Muslims or the head of the Islamic Center in your country may be her Waliy. It is not permissible for her mother to be the Waliy of her daughter in her marriage contract. May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.