Thanks for the module.

I see that you're using the Msf::Exploit::Remote::SMB mixin, this means that you don't actually have to register the SMBUser and SMBPass options, because they're already pre-registered by the mixin. Here's the code that does that:

https://github.com/rapid7/metasploit-framework/blob/master/lib/msf/core/exploit/smb.rb#L57

To see these options in msfconsole, type "show advanced", and you should see them.