I cannot find any information about her. Her husband Vladimir was a General in the Russian army during the Napoléonic wars.
The dual sleeve worn by Varvara was all the rage in the 1820s and early 1830s. Her dress is Napoléonic and she looks like a teenage girl (click here for an 1802 portrait of her), dating this to maybe 1810. This portrait could record one of the early uses of dual sleeves and evidence that the fashion appears in Russia first.