We are sorry that we did not inform him my brother suddenly join our trip. So we are five people arrived there. Luca charged us EUR50 /two night for one extra people. It quite surprised that when I checked back the charge for extra people per day is GBP14 (EUR20) per person per night, which means he charged more than the original price.
But Luca is a quite considerate host. He provided a pick up service which charged EUR 20 and the free detail information around the apartment. We had a great vacation there.
*More information for the guest who wants to know how to get to the apartment*
the Venice Tourist Travel Cards (ACTV) is included the bus and boat. So you can take the bus to the apartment which is free of charge if you already have the Venice ACTV!