No, Queen Elizabeth II is not from the House of Stuart. She is from the House of Windsor. The House of Stuart ruled England, Scotland, and Ireland from 1603 to 1714. The last monarch from the House of Stuart was Queen Anne, who died in 1714.
The House of Windsor was established in 1917 when King George V changed the name of the royal house from the House of Saxe-Coburg and Gotha due to anti-German sentiment during World War I. Queen Elizabeth II is the longest-reigning monarch in British history and has been a part of the House of Windsor throughout her reign.