Benjamin's Persoonkaarte seems to suggest that he died in "Orng: Berlijn" which likely is a reference to Oranienburg, a small town outside of Berlin, Germany where Sachsenhausen concentration camp was located. This is presumably where Benjamin perished and not in Berlin proper.
Benjamin was on the "Diamond Transport" that departed Westerbork on 19 May 1944. Over 200 highly-skilled diamond workers and their families were on this transport to Bergen-Belsen. The Reich planned on constructing a diamond factory in Bergen; the deported Dutch diamond workers had relatively nice barracks and wore normal clothes (according to other Bergen prisoners, anyway).
At the end of 1944, the Reich abandoned the plans to build a diamond factory at Bergen. The diamond workers who were residing in the diamond workers barracks at Bergen were dispersed among different concentration camps as general labor. Many were transferred to Sachsenhausen concentration camp where they perished. Benjamin Cohen was likely among them.