I am not Russian, but I'm *guessing* this might be related to the popular Russian name
Zhenya, an unisex nickname for Yevgenia (f.) or Yevgeniy (m.) Russian for
Eugenia or
Eugene.
A further diminutive of
Zhenya might be Zhenyushka (Zhen-yooshka, first syllable stress), which might have been transformed into Zenouska.
Regards,
Rosomaqa