Hello Kissan,
not sure if you already fixed the issue but I also discovered a few of these hits on some client websites.
First I use the plugin Redirection. This provides me with the options of login and redirecting sites. It also has a good 404 login.
I also use Ithemes security. I believe it came with WP 4.0. Not sure. But this gives you the option to block IP addresses automatically if they generate a lot of 404 hits in a short period of time.
Hope this helps!
Laurens
