What is the name of sandipani muni's wife ?
According to the Sri Radha Krishna Ganodesha Dipika (A lamp to see the associates of Sri Sri Radha-Krsna) by Srila Rupa Goswami, the name of Sandipani Muni's wife is Sumukhi devi.
The following lines mention it
Madhumangala has a slightly dark complexion. He wears yellow garments and a garlands of forest flowers. His father is the saintly Sandipani Muni, his mother the chaste Sumukhi devi, his sister is Nandimukhi-devi and his parental grandmother is Paurnamasi-devi. [63-64]
Nandimukhi-devi has a fair complexion and wears exquisite garments. Her father is Sandipani Muni and her mother is the chaste Sumukhi-devi. Her brother is Madhumangala and her paternal grandmother is Paurnamasi-devi. She wears various jeweled ornaments and she glows with youthful luster. [98-99]