George B. Kebe, 22, of 2363 Ainger Pl. SE, was sentenced in D.C. Superior Court yesterday to a prison term of from 26 years to life for the murder last year of an 18-year-old Georgetown university student.

Assistant U.S. Attorney John Hume contended that Kebe should be given the maximum adult prison sentence for the murder of Maureen McGrath, largely because of his long criminal record.

Kebe's lawyer, James E. Joyner, urged Chief Judge H. Carl Moultrie I to sentence the defendant under provisions of the Federal Youth Corrections Act, which would have resulted in a sentence of indefinite duration with no minimum. If sentenced under the Act, Kebe would have been eligible for release within a year.

Last December, Kebe pleaded guilty to the murder March 10, 1979, of McGrath, a freshman Foreign Service student at Georgetown. He described in a signed confession how he repeatedly stabbed McGrath with a pair of scissors after he strangled her with a scarf at the Regent Place men's shop at 1641 Wisconsin Ave. NW, where she worked part-time as a clerk.

Kebe also pleaded guilty to the robbery of Baracat Imports, a shop at 2030 T St. NW, three days after the murder. In addition, he pleaded guilty to embezzling approximately $750 from the Dart Drug store at 1901 Wisconsin Ave. NW., where he worked as a cashier until shortly before the murder.

Moultrie sentenced Kebe to the maximum adult sentence of 20 years to life for felony murder. In addition, he was sentenced to 4-to-112 years for robbery and two years to life for embezzlement.

The court ordered that the sentences be served consecutively.

Hume advised the court that Kebe's criminal record dates to 1968, when he was involved in a burglary. The prosecutor also pointed out that the youth act had been invoked twice in Kebe's behalf, once in 1975 and again in 1976.

"Yet less than four months after he was paroled . . ." Hume noted, "the defendant commited the brutal crimes for which he is to be sentenced by this court."