A tummy tuck would give you excellent results and is the only way to get rid of the excess skin of your lower abdomen that you have.  The reason that this happens to some women is that the skin of the stomach stretches during pregnancy and does not completely shrink back as it does in other women.
When you are researching tummy tucks or abdominoplasties make sure that you find a surgeon who is American board certified in plastic surgery and one who does NO drain, rapid recovery tummy tucks.  This significantly reduces complications and increases your chances of getting a great result.