Which of the following is the feminine form (Stri-linga) of the word 'Vidhur' (विधुर)?

In Hindi grammar, a man whose wife has passed away is called 'Vidhur' (विधुर). Conversely, a woman whose husband has passed away is called 'Vidhva' (विधवा). Therefore, 'Vidhva' is the opposite gender (feminine form) corresponding to 'Vidhur'.