I am guessing you have a 9752 or 9853 - is it a square main system case or an oblong one?
The 9930 keypad is obselete, but a 9941 or better yet 9943 if you want fob will do the same job.
You'll have to wire the keypad, of which you can have 4, back to the nearest other keypad, expander, or the panel.
The keypad only uses 4 wires so assuming it's all done in 6 or 8 core wire, you could use the spare, as long as
they aren't already in use, for the EOL door contact.
Or, as it's already a wireless system, add another wireless door contact? Even the newest Eaton slim RF door contact will work with an
older system.
(You could even add an expander if you are wiring to the nearest expander or keypad, but seems a lot for just one zone, and it would have to
be the larger 9853 system for there to be 'room' for it)