Kennedy Center honoree Irene Dunne, who was unable to make it to the gala evening Sunday, is in Georgetown University Hospital recovering from the aftereffects of a stomach disorder that left her dehydrated. Suffering from back problems, Dunne took some medication for the pain that apparently upset her stomach.

The star of some 36 movies, including "Cimarron" and "I Remember Mama," the 80-year-old actress was able to attend only the Saturday night State Department dinner. Fellow honoree Bob Hope had offered Dunne the use of his private airplane Sunday night to take her home, but it was decided she should be treated here. At Georgetown, Dunne is receiving liquids intravenously to alleviate the dehydration and is listed in stable condition. A hospital spokesman said she is expected to be released in another two or three days. Bill Frye, Dunne's producer, said she should be out Christmas shopping by Thursday. '60s Nostalgia

All those answers undoubtedly will be blowing in the wind once again at the Kennedy Center next year when nostalgia will reign at a 25th-anniversary tribute to Peter, Paul and Mary, the group that sang many of the anthems of the 1960s. Sponsored by the Free South Africa Movement, the evening promises to bring out many of the names that were such a significant part of the social movements of the time.

The Feb. 25 Concert Hall anniversary celebration will be in two parts. The first half will be a tribute to Peter, Paul and Mary that will include singers Judy Collins and Odetta and activists like Coretta Scott King, widow of the Rev. Martin Luther King Jr., and Cesar Chavez, president of the United Farm Workers Union. The remainder of the evening will be Peter, Paul and Mary singing those songs that will bring a lump to the throats of graying liberals who will remember marches, demon- strations and concerts when they were committed to civil rights and other social causes. End Notes

Kennedy Center honoree choreographer Merce Cunningham had a big evening Sunday. He was sitting in the Presidential Box of the Opera House with his fellow honorees when the head usher received a call and passed a note to him. That's when Cunningham learned that he had just won the Laurence Olivier Award in London, a high honor in the British theater world comparable to the Tony. He received the award for "Pictures," voted the best dance production of the year . . .

Danita Xavier Manley, 35, executive director of Model Management/John Casablancas Agency, was crowned Mrs. Maryland Sunday evening and will compete in the Mrs. America Pageant in April . . .

On the fifth anniversary of the murder of former Beatle John Lennon Sunday, singer/songwriter Harry Nilsson ("Everybody's Talkin' ") presented the National Coalition to Ban Handguns headquartered here with a set of 20 lithographs done by Lennon. From a series called "Bag One," produced in 1970, the majority of the prints are of Lennon and his wife Yoko Ono. The coalition plans to auction the set sometime next year and a spokesman there said it is expected they will bring at least $25,000 . . .

House Speaker Tip O'Neill celebrated his 73rd birthday yesterday with a party in the Capitol and Sen. Ted Kennedy showed up to present O'Neill with a gift -- the sizable jersey of Chicago Bear William "The Refrigerator" Perry. The jersey was No. 72, close enough to the right age, and the rotund speaker allowed as how it might fit and then some . . . And that was the speaker, being the good grandfather, sitting in the back row of the Tenley Circle Theater Sunday watching "Santa Claus: The Movie," with his grandchildren at the Christmas Party Congressional Family Day. If only Tip had a white beard, he could have been Santa for the day . . .

Fashion designer Perry Ellis fainted last night during the opening reception for the Metropolitan Museum of Art's exhibition of Indian costume. After coming to, Ellis said he had mixed a pill and a drink. He then went on to attend a gala dinner for 900 . . .

Tommy Curtis, one of Washington's better-known disco- and singles-bar owners, has decided to get out of the business. He has sold his interests in Numbers and Annie Oakley's, saying he could "no longer take the intense pressure of wet T-shirt contests, disco fashion shows and checking the IDs of girls whose mothers I dated." Then he added, "I may even write my autobiography of 15 years in the Washington singles-bar scene entitled "Hey, Tom, Are There Any Women Here Tonight?" . . .