Mrs. Bluveridge is the proprietor of the Admiral Benbow Inn in Muppet Treasure Island. She's a tough and rugged lady, and holds her own with the shady characters who patronize her establishment. She also has a running gag in which she can hear conversations from far distances and continues them with a negative remark. This usually leads to other characters exclaiming in shock, "How does she [bloody] do that?"
Mrs. Bluveridge is awakened by Jim Hawkins during the pirates' attack on the inn, and after allowing Jim to escape, she takes on a swarm of pirates, beating them senseless. She appears again (this time with several pirates on her) when Jim and his friends proceed to leave the inn, advising them to run for it and assuring them she'll be fine. These acts thus show that, despite Mrs. Bluveridge's stern and overbearing demenor and her strict approach towards her wards, she nevertheless does genuinely care about them and their safety.
The character was created especially for the film, and did not exist in Robert Louis Stevenson's original novel Treasure Island. In the novel, the protagonist Jim Hawkins is being raised by his mother; in the Muppet film adaptation Jim is an orphan and Mrs. Bluveridge is the closest thing he has to a guardian.