When addressing GAP issue during the interview, try not to appear as if it's your fault that happend. State your reasons and move on. Try not to drill on it. Try not to make a big deal or a heavy subject.
When stating your reasons, I think you ought to mention your mother's passing. People would understand that and feel for you. It's reasonable that you then decided to take some time off and took care of your family after her passing. Since the job market wasn't ideal by the time you were ready to enter the market, you decided to wait and at the same time to work on your skills. Prepare some good subjects that you either took course for or did self training on during that perios of time. People would like to hear that.