At least look at two one-way tickets before committing yourself to the change fees. Sometimes the one-ways aren't prohibitively expensive.

Change fees probably vary by airline, but you should determine the amount before you purchase if you opt for that method.

If your wife has any miles accumulated, sometimes one-way mileage tickets can be obtained.

The airport code for Chennai is MAA. You can do all sorts of interesting research on http://matrix.itasoftware.com or Google flight search.

Do look at various airports in the San Francisco area if they will work for you - SFO, OAK and SJC. Sometimes there can be surprising differences in the rates for departing from different airports.