Answer:
A car was being driven by my mother.
Step-by-step explanation:
When doing active to passive:
do=is done
am doing=is being done
did=was done
was doing=was being done
have done=has been done
had done=had been done
will do=will be done
am going to=is going to be done
must do=must be done
should have done=should have been done
(Hope this helps)