You can not find BMI as variable in any of the data set. You will will always get Weight and Hieght either for child, men or women. The Biomarker for men will be available from HIV/Other Biomarkers datasets from DHS website.
Weight and Height variables are also not available in the Men's file so I use household member/person (PR) file to use height, weight & BMI and then merge it with men's file. Thanks for your comments Arpit Singh Ji.