The 3D Cursor is a very handy tool. You can use it to set a temporary center for motion, rotation, scaling, and use it to define the center of an object in whatever location you want. Now, you are going to use it as a center for scaling:
Load the file of Suzanne that you saved after grouping her eyes. Make sure that you are looking at Suzanne from the front view.
Deselect all the vertices.
Use the circle selection or the Lasso tool to select the vertices in Suzanne's ears.
When you have Suzanne's ears selected, use the LMB to click on the second button to the left of the mode selector in the 3D View header, as seen in the following screenshot. A Pivot Point menu pops up. It lists the ways you can set the center of scaling and rotation. Select 3D Cursor with the LMB.
First, start by making sure that the 3D Cursor is in the center of the Blender world.
Press Shift + S to bring up the Snap menu, as shown in the following screenshot. Select Cursor...