Is a wife's working for an insurance company, given her inability to leave the job due to her husband's refusal and financial need, and in light of the high cost of living and the futility of her attempts to transfer to departments far from usury, considered a case of necessity (ḍarūrah)?

If the insurance you work with is commercial, based on gharar (excessive uncertainty), gambling, and usury, then it is forbidden, and it is not permissible to work in it. You are not obliged to obey your husband in remaining in this forbidden work, and the husband is responsible for providing for his family. However, if the insurance is takaful (cooperative and mutual), then there is no objection to working in it, provided the Sharia-compliant regulations for women's work are observed.