For vRealize standard, the components are operations manager, log insight and business.
for vRealize Business, do we need to install vRealize automation or vidm ? or can we install vRealize business as a standalone ??
Yes, vRBC still needs an authentication mechanism, so that's either with vRA or with vIDM. Note that in latest vROps some (but not all) vRBC functionality has been included, and vROps does not need vIDM separately.