Yes it is possible to use PIC16F877A to generate 50 Hz PWM signal to drive servo. In the CCP module, generating PWM with frequency of 50Hz is not possible with clock frequencies in the MHz range, where you should use the compare part of the CCP module.
Because of that I have used 1843200 Hz crystal to be able to generate 50Hz signal but in that case I couldn't communicate with pic by using Rx pin (I am using pic16f877a)
Instead of lowering clock frequency (thereby increasing instruction time) so that you can use the PWM part of the CCP module, just use the compare part of the CCP module along with Timer 1.