How to get shutdown button in login screen–Windows 7

You can try to change a registry value in the registry editor and check if that resolves the issue:
a.       Just click on the Start.
b.      Type regedit on the search box and hit enter.

c.       Navigate to the following Key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System .
d.      Now look for a key shutdownwithoutlogon on the right hand side.

e.      Double-click on the key and change the value to 1.

Editing registry might cause irrecoverable damage to your operating system, ensure you have an back up.