Is it permissible for a marriage contract to be witnessed by one man and two women, or by four women? And is it a condition that the witnesses to the marriage contract be Muslim, especially if the bride is from the People of the Book?

Witnessing is a condition for the validity of marriage. Many scholars stipulate two Muslim male witnesses who are just, adult, and sane. The testimony of women is not permissible in marriage. The two witnesses must be Muslim, even if the wife is a dhimmi (a non-Muslim living under Muslim rule), and this is the view of the majority of scholars.