My requirment is that, I want run BLE scanning service to scan Eddystone beacon even my app is in background/forground or terminated/killed by the user. is this possible in iOS?
You cannot re-launch an app from a killed state on iOS with Eddystone beacons because these beacons are detected with CoreBluetooth APIs which do not support re-launch from a killed state.
What you can do is use a beacon that transmits both Eddystone and iBeacon. The iBeacon is detectable with CoreLocation APIs, which offer the unique ability to re-launch an app into the background from a killed state on iBeacon detection.
Once launched into the background by iBeacon., the Eddystone beacon can be detected.