How Can Xbee S2C (end point) be used to send analog data from 3 sensors to the coordinator?

I am using 3 moisture sensors and want to send data one by one from a single End-Point module to the Coordinator.Is it possible to do so and if yes,then how?

No, the XBee module samples all enabled ADC samples at the same time. So on your coordinator you would get a API frame indicating how many samples were taken, which lines are enabled and then the ADC values for each enabled line.