To solve this problem, we need to identify which organism belongs to the family Muscidae.$\newline$Let's analyze each option:$\newline \bullet$Fire fly: Fireflies are insects in the family Lampyridae. They are known for their bioluminescence.$\newline \bullet$Grasshopper: Grasshoppers belong to the order Orthoptera and are not part of the family Muscidae.$\newline \bullet$Cockroach: Cockroaches belong to the order Blattodea and are not part of the family Muscidae.$\newline \bullet$House fly: The house fly, scientifically known as Musca domestica, belongs to the family Muscidae.$\newline$Therefore, the organism that belongs to the family Muscidae is the house fly.$\newline$This corresponds to Option 4.