Is it permissible for a woman who has no guardian (wali) to contract an 'urfi marriage without one, especially since Abu Hanifa permitted a woman's marriage without a guardian, and is a Kitābiyyah (woman of the Book) treated like a Muslim woman in this case?

A secret marriage is invalid if it takes place without a guardian (wali) for the woman, and this is the view of the majority of scholars. A guardian is required for both Muslim and Christian women, in the following order: the father, then the paternal grandfather, then the son, then the full brother, then the paternal half-brother, then their sons, then the paternal uncles. If she has no eligible guardian, the Muslim judge (qadi) may marry her off with her permission. The knowledge of the family is not a condition for the marriage, but the contract must be concluded through the woman's guardian and in the presence of two Muslim witnesses.