The landslip happened in the early hours of Sunday at the Markos Studios, a family-run beachside complex of rooms to rent built under a rocky hillside at Ierapetra.
Police said the rock destroyed two rooms. The victim's 51-year-old husband was in a different room and was unhurt.
The 47-year-old woman and her eight-year-old son were buried under the debris.
About 50 firefighters rushed to the area and managed to rescue the boy after an hour of digging through the rubble. The boy's mother was found dead.