Depends on the version of C# you use: from C#6 you can use
cmd.Arguments = $" /c netsh wlan set hostednetwork ssid={ssid} key={pass}";
But before that either
cmd.Arguments = " /c netsh wlan set hostednetwork ssid=" + ssid + " key=" + pass;
Or
cmd.Arguments = string.Format(" /c netsh wlan set hostednetwork ssid={0} key={1}", ssid, pass);
will do it.