My specific response will predominately based on where we're sitting, near the center or near a side, near the front or near the rear. The doors are virtually always around the outside walls and the rear. As soon as the shooting starts there will be a mad rush from the center to the outside walls, jamming any between table aisles. As soon as the people start moving there will probably be very few to no shot opportunities, at least until the crowd begins to clear in any particular area. In addition, those shot opportunities may vary from five or ten yords to more than fifty yards
If seated near an outside wall/door, put the wife out the door. If seated near the center, put her under the table. That will give her some protection, not only from getting trampled, but also from fire. The protection from fire will come from both the upright escaping people between her and the shooter and the shooter being unable to see her. In these events the table cloths are usually mid length and the tables are spaced close enough that it is nearly impossible to see under a table not in close proximity.
WIth the wife taken care, respond to the shooter. If along a side move toward the front for a closer/available shot. If near the center, two possiblities. First, attempt to move forward, below table level for concealment until a shot is available. Second, especially if at a reasonable distance and moving forward is not possible due to the crowd, more people being shot and being of older persuasion without the responsibilities of younger children and a young family. Jump on top of the table. This will give me the best possibility of a clear shot and draw the attention of the shooter away from the crowd to me. Unload a wall of lead on him.