Which parsing of بِزَيْنَبَ is correct?

Causes of Diptote Status — Femininity and Its Conditions

• Bi is a preposition; Zaynab is genitive with fatḥa
• Bi is conjunction; Zaynab is accusative
• Bi is a verb; Zaynab is subject
• Bi is vocative; Zaynab is a vocative noun