Are you referring to the Map Inquiry category in the Controls Commands dialog of the ToolbarControl? Is that what you do not see? I do not know of a tool called Map Inquiry but I do know of a category with that name where we can find map inquiry tools to add to a MapControl Engine application, e.g. Find, Identify, Measure, etc.
Also, you say you are working with version 9.0 of ArcGIS Engine? ArcGIS 10.0 is the current release and 9.3.1 was the release prior to that. I cannot check right now in 9.0 because such version may have required a version of Visual Studio that I do not have.