A look at upcoming events in LOS ANGELES COUNTY

SAVE A LIFE--The Walnut Valley Chamber of Commerce is sponsoring a Halloween masquerade party Monday from 6 p.m. to 11 p.m. with a difference: The $25 admission fee will defray the cost of locating bone marrow donors for two teen-agers dying of leukemia. The party will be held at the Pomona Valley Mining Co.

TRICK OR TREAT--An estimated 300 police officers have been assigned to cover the annual Halloween Parade Tuesday on Hollywood Boulevard in an effort to avoid a repetition of last year’s riot.

POLICE COVERUP--Lawyers for the city of Torrance will appear in Los Angeles Superior Court Tuesday to ask Judge Abby Soven to overturn a $6-million award to a San Pedro family last month. The jury found Police Chief Donald Nash and five officers responsible for covering up for the possible drunk driving of a colleague involved in a fatal 1984 traffic accident.

MONEY WOES--Additional Compton city workers may face layoffs after a City Council workshop scheduled for Tuesday to discuss the city’s financial problems. About 85 city workers were laid off in July.