Final answer:
The return command allows the control to return back to the calling script once the called script is completed.
Step-by-step explanation:
The command that allows the control to return back to the calling script once the script being called is completed is the return command. When the called script finishes executing, it will return a value to the calling script. This allows the calling script to continue executing from where it left off.
For example, if you have a main script called 'main.py' that calls another script called 'helper.py', you can use the return command in 'helper.py' to send a value back to 'main.py'. Once 'helper.py' completes its execution, the control returns to 'main.py' and continues executing the remaining code.