Here are the steps to add DataViewer in DataFlowTask.
Step 1: Select a Particular path, Right Click and Click DataViewers..... option
Step 2: Select DataViewers from the left pane and Click Add button.
Step 3: Select grid and click Ok, and ok in DataFlowpath Editor window.
Step 4: Execute the package and you can get the DataViewer window as below in the picture.