It's an inquiry conducted by the US House of Representatives.
Here in the US, it's extremely common to shorten the full name to just "House" or "The House". Context makes it clear to anyone familiar with the US system of government. Of course in written usage, capitalization also helps clarify.
Similary, the United States Senate is referred to as "The Senate" or "Senate", although you don't really save as much as it's relatively short already.