Those are missing the screws that thread into the holes. I don't think a banana plug will work.
Find screws that will fit. You can use bare wire (carefully) or use spade lugs with those speaker terminals. You don't want a short between the terminals.
The stereo could be modified with 5 way binding posts to accept banana plugs or heavier bare wire. If you can solder it's not too hard.
Hard to tell with the resolution, but if they are machine threaded it could be just missing the screws so it could accept bare wires or fish-eye / U crimps if you get new screws for it.
Those are missing the screws that thread into the holes. I don't think a banana plug will work.
Find screws that will fit. You can use bare wire (carefully) or use spade lugs with those speaker terminals. You don't want a short between the terminals.
The stereo could be modified with 5 way binding posts to accept banana plugs or heavier bare wire. If you can solder it's not too hard.
I'll bet that GND (ground) screw is the same size, using a plain-old manual philips head I would try it carefully and see if it will fit. If so, bring it over to home depot and match it up. #8-32 is a popular size, could be what you need.