why we must to follow 50ohm and 100ohm impedance in PCB boards? is it a standard value for all device input and output impedance?
It's a de facto standard, and it doesn't apply to everything.  For example, the USB standard specifies 90 ohm differential impedance instead of 100.  Maintaining the proper impedance is important for minimizing reflections at high frequencies, so controlled impedance connections are usually only required for high speed/high frequency signals such as RF and high speed serial.