Thank you for contacting Mearto. Unfortunately, this is not an authentic Nandalal Bose painting. I have located the original that this one imitates. The link is below. You can see that the style is different.

I have also included a link to more of Bose’s work. You can see that his style is more dreamy and he doesn’t use the bold outlines that are seen in your painting.

Based on sales of similar paintings as this, the Fair Market Value is between $50 and $100.

Bose's Shiva
https://www.wikiart.org/en/nandalal-bose/siva-drinking-world-poison

Other Bose works
https://www.sothebys.com/en/search?query=nandalal%20bose&tab=objects