Try this:
- Set the keyboard to “Terminal” view.
- Tap the
Altkey, then the letterv(to enter theViewmenu, which is invisible to you at the moment). - Enable
Menubar. - Don’t forget to unclick the
Altkey.
EDIT: Nevermind. Doesn’t seem to work if Menubar is not visible…and I just put my Nemo in the same state as yours! 
EDIT2 (Solution): gsettings set org.nemo.window-state start-with-menu-bar true
ref: https://askubuntu.com/questions/1325426/nemo-menu-bar-doesnt-show-up