I think your attempt to track persons by RFID has a limited use in real circumstances. The concept of RFID rather is that RFID label can be read if it comes close to the appropriate reader. If you attach a RFID to a person, its presence and identity can be read at RFID reader locations but not at other places.
Using a cell phone to track persons is better as the location can be almost uninterrupted. Some cell phones include a GPS module, to locate it anywhere.
There are alarm systems for sick or elderly people available today, with alarms connecting to a telephone and then to a service that can locate and help a person fast like an ambulance.