Who received the bronze star in the 45th infantry division in World War 2?

Try the "American War Library." If you have a copy of his Discharge papers and you know the General Order that issued the BSM, then you can request a copy of it from the National Archives. If not, they you would have to research the files or hire someone to do this. Note, that in 1947 there was a rule change that awarded the BSM to any soldiers who fought in combat as an infantryman and had been awarded the Combat Infantry Badge. So it is possible that he did not earn the BSM for a specific action and after the war he ordered his discharge papers, it would show he earned the BSM.