Suszec birth certificates from year 1891 can be found in the national archives in Pszczyna, Poland. Unfortunately they are not accesable by Internet, so if by any chance you’ll be here in Poland you should go there and order an archive:
“486/0 Urząd Stanu Cywilnego w Suszcu”
About your grandfather, its more complicated matter, if you have more specific date of death you can order his death certificate directly in Suszec because certificates from 1909 and above are not yet in general archives but in registry office of particular cities.
Anyway this matters will be most likely to handle only in Poland but you can try call or write to this places so they may help you and guide you further.