ANSWER:

What the elders are telling you is all baseless and not from Islam. 

Having jinn and shayateen in toilets and bad places is 24/7 and not only limited to maghreb time.

We say the athkar and enter it any time of the day and night.

QUESTION: Is it true that shayateen & bad powers live in dark or dirty areas?, bcz on based of this reason the elders in my family prohibited us to go toilet(urinate/shower )at the time of maghrib or Azaan & forced us to switch on the lights of whole house on based to stay away from shayateen.