In my opinion, EVERYONE should complete an Advanced Health Care Directive as soon as possible regardless of your age. In Calif you can go to any Passages Program or any hospital and pick up a blank AHCD and fill out it out. You must have to people/friends who are not related to you to witness and sign it. There is no cost to you. Everyone in your family should have a copy, one should go into a safe deposit box at your bank, one should be in an envelope and attached to your refrigerator in case medical/police people have to come to your house and finally you should carry a copy in each of your vechicles.
When your parents are older, you should make sure you are also listed as having power of attorney on all their financial accounts while they still have "legal capacity".
Ombudsman