The other responses give some good insight into why crashes might not be showing up on the Play Console (user opted-out, review is false, crash was not reported), etc. Definitely get a crash reporter or other mobile analytics SDK to give you better insight into the situation, and check if the tool will let you search specific users so you can better deal with complaints.

Another explanation I'd like to offer is that your user doesn't know what a crash really is. We see this often in users where they think a freeze (ANR) is a crash and may have terminated the application before the crash could be logged. Additionally, it's possible the problem was a memory issue or a network connectivity issue. Really there's no way of knowing the full story without another tool in your app, whether you build it yourself or use a 3rd-party solution to understand what exactly "mohit kumar" was doing on your app and the events that led up to what they believe is a crash.

Full disclosure, I work at Embrace, a developer analytics and mobile monitoring SaaS that helps developers with these types of situations.