Decide how long your trip is actually going to be, at a minimum. Many insurance companies require your trip to be at least ten days in order to cover you.
Do a bit of packing. Is the student going to pack lightly or heading abroad for a long time and therefore taking valuables, like a laptop, ipod, digital camera, or jewelry? If the student is taking valuables, consider buying a traveler's insurance policy that has a property & casualty component. If your valuables are stolen or damaged, you can get them replaced.
Does comprehensive coverage sound like something that will give you and your family members peace of mind while the student is abroad? If so, consider policies that offer a personal liability component. This can be important, as cultural differences can sometimes lead to legal concerns abroad. Some traveler's insurance policies include personal liability as a benefit - and don't charge you extra for it!