Law / My grandfather left Poland after WWII and emigrated. Question About Polish Citizenship [10]

My mother's family left Poland after WWII an emigrated to Brazil. Recently I've been researching if its possible for me to obtain a Polish citizenship. The main problem I've ran in to is that theres a possibility that my grandfather may have become a Brazilian citizen in order to not be drafted to the polish army. I am still looking in to weather that actually happen since he died in 1950 so I don't have much information on him. Anyways does anyone know if his naturalisation would make me ineligible for a Polish citizenship?

PS: While my grandfather is not alive my mother is, so I am assuming that she can get a Polish citizenship and subsequently so can I. Is this correct?