The combination is actually not even hard to see, especially not for FM. 

Sincere commiserations.Cheers from Melbourne.

Sorry to hear about your loss, but I'm curious as to why Black resigned in the final position?  

Not only are there several variations after which Black is only a pawn down (with some positions looking very drawish), but they have a simple sequence whereby they are up a bishop;

20...Qxc4 21. fxe7 (as you recommend in your notes) Re8 22. Rxc4 (forced) 22...Bxd1

After this, White is the only one who should consider resigning, although he can fight for a draw with 23. Rc7.  (Black should still win easily with solid play)

Very sorry about your son. 

Sorry, man. 

Dear John,
Very sorry to read about your son.
Sincerely wishing all the strength to help you through at this time.
From your old Chess friend(s) at the former Balcktown Workers Chess Club.
Peter 

I will. Thank you.

Nice combination. Sorry to hear about your son.

where`s the last move if he plays

fxe7

KaPow!! Nicely done. Keep'em coming.

!! move