In "The Cask of Amontillado," Montressor, the narrator, explains:
There were no attendants at home; they had absconded to make merry in honour of the time. I had told them that I should not return until the morning and had given them explicit orders not to stir from the house. These orders were sufficient, I well knew, to insure their immediate disappearance, one and all, as soon as my back was turned.
This, of course, assures that there will be no servants in the palazzo when Montressor arrives with Fortunato. It also shows that Montressor employs disobedient servants who have no respect for him.
The fact that Montresor was only concerned about getting rid of the servants that night, in addition to the fact that the palazzo appears to be empty when he and Fortunato arrive, is a subtle way of indicating Montresor's loneliness. He doesn't have to worry about encountering any family members because there are no family members. Any family he may have had at one time would be among the skeletons lining the walls of the catacombs below his palazzo.
When they are underground, Montresor tells his intended victim:
"You are rich, respected, admired, beloved; you are happy as once I was. You are a man to be missed. For me it is no matter."
This may be indicating that Montresor is not rich, is not respected (even by his servants), is not admired, is not beloved. Montresor is not a man to be missed because there is nobody at home to miss him. His large, possibly decaying palazzo is nearly empty.
Why does he keep such a large house and a staff of servants, however disrespectful and unreliable? Venice is a decaying city. The palazzos may be relics of the city's past glory. Montresor indicates that his palazzo is situated at some distance from the city and that the catacombs are under the river--probably the Po River.