If no referees show up at the game, this is the protocol:

a) See if anyone present at the match is currently certified. If they are, and are willing, they should be the referee.
b) If someone was recently certified, they can be used as well but currency is important.
c) A volunteer with a solid knowledge of soccer can be used… generally this would mean a coach or an assistant coach.
d) Anyone willing to call fouls.

In all cases the two coaches should get together before the match and agree on how this will work.
IN ALL CASES THE SAFETY OF THE PLAYERS IS OF THE UTMOST IMPORTANCE.