The .img file you're referring to is likely related to the installation process of Windows 95. Specifically, I think you might be interested in the WIN95 IMG file, which is a CD image file.
Here's an interesting feature:
This file allows users to create a bootable CD from it, which can be used to install Windows 95 on a computer without a working operating system. windows 95 c.img file download
Back in the day, this was a common way to distribute Windows 95, especially before widespread internet access and USB drives made it easier to share and install operating systems. windows 95 c.img file download
You're interested in learning about a classic piece of computing history! windows 95 c.img file download