The Mudroom is a room inside the Gloomy Manor. It is set next to the Entrance and the Mudroom Exterior. In the first mission, it houses a Key needed to enter the Guard Hall or the Foyer. Several spiders will appear here at various times as well.
The Mudroom has two dressers, two chairs (one of which has toppled over), a table, a furnace, and a fan which can be spun by Luigi much like in the original game. There is a rug in the center of the room that can be rolled up to reveal a panel in the floor. Stepping on this panel will uncover a secret area that will spit out coins and bills. There is also a painting in the lower-right hand side of the room that has been taken down to reveal an alcove with coins inside. The coats that are hanging on the hooks may be taken down for one bill each. There are also windows that can be seen out of into the Mudroom Exterior.