In this file: modules/xdirectory/include/search.inc.php contains the SQL statement that XOOPS uses for searches. I've added the category title but when it does a search it lists every result as a category name and not the name of the actual busines.
see my example here and tell me if that is what you're looking for. http://www.folsomliving.com
If it is I'll send you the code.
-Builderb