The Tygon hose runs from the top of the fuel pump to that carb fitting. In case the diaphragm fails, gas in vented into the carb instead of your bilge to reduce fire hazard.
If your fuel pump doesn't have the fitting, the pump is a non-marine version with a vent. The vent turns into a gasoline geyser and that's not good.
Is there a loose hose on the fuel pump?