I rented out my califorinia house to a couple in July 2012 on a one year least. They have been late with rent the last three months. This whole ordeal is a nightmare. My parents need a place to stay. Can I break my tenants lease?

No but you can and should have started the eviction process the first time they were late... now you have to wait until they are late again to do it.

What part of California... unfortunately some places require 60 days notice to vacate before you can go to court to have it enforced... others its 30 days. (for example in Florida its two weeks).

Have them properly served with the correct papers the day they become late the next time... because it HAS to be done according to the letter of the law... or they will be able to drag this out.

If you give them a pay or quit notice they can postpone by paying. So give them a 30 day vacate notice citing chronic late payments as the grounds. If they go to court to fight it, the fact that you plan on moving a family member in will help you.