From the Super Mario Wiki
Mrs. S, or Mrs. Shroomlock, is the wife of Shroomlock and a housekeeper in the game Mario Party Advance. She is a Toad with a purple cap. Additionally, Mrs. Shroomlock is a huge gossip; her only purpose in Mario Party Advance is to tell gossip that may help the player on quests when she is optionally visited. The ending of the game states that she became addicted to infomercials.
Names in other languages
Mrs. Shroomlock is the only character in the game the player does not have to visit if the player wants to complete all of the quests. However, if the player wants to meet every character, they must meet Mrs. Shroomlock in Shroomlock House.