Alice Marran Cyr, 70, a native of Washington and a longtime resident of this area who later became a social worker in New York, died of congestive heart failure Thursday at the Good Samaritan Hospital in West Islip, N.Y.

Mrs. Cyr was a graduate of Georgetown Visitation Convent in Washington and of Manhattanville College in New York. After college, she returned here and married Donald James Marran, a lawyer in the Justice Department. The couple lived in Washington and later in Alexandria. In the 1950s, they moved to Babylon, N.Y.

Following Mr. Marran's death in 1961, his widow began her career as a social worker with the Suffolk County, N.Y., Social Services Department. sIn 1968, she married Walter J. Cyr, a businessman, and settle in Stamford, Conn., where she continued her career in social work. After Mr. Cyr's death in 1969, Mrs. Cyr moved to West Islip and resumed her work with the Suffolk County Social Services Department. She retired in April.

Mrs. Cyr was a past president of the Baxter Guild at Good Samaritan Hospital.

Survivors include three daughters, Emily Marran Surman of Fairfax, and Sarah Noble and Letitia Marran King, both of Babylon; two sons, James Emery Marran of Bernardsville, N.J., and Donald Michael Marran of Bay Shore, N.Y., and 15 grandchildren.

The family suggests that expressions of sympathy be in the form of contributions in Mrs. Cyr's name to the Good Samaritan Hospital, West Islip, N.Y.