Question: which of the three shear connections (beam/column) below will require diagonal bracing?
Usually, there is no need for diagonal bracing. The details A and B are not suited for diagonal bracing.
Detail C for large span beams under heavy loads can have triangular stiffeners welded on the bottom between the two sides, but that kind of connection is not encouraged. If the girder or heavy beam connects to support or column, custom-designed connections are employed because of limitations on the detail C type configuration.