I had a friend who was recently locked out of the house he was renting with an eviction notice that said the home had been foreclosed on. He says that he had no idea that the owner was even behind on any mortgage payments and that he basically has no way of getting any of his money. Is there a way to make sure that this does not happen to me and my family?

First he can not be "locked out" that is not legal and he can merely go in.

They can after it is foreclosed, give him a eviction notice, and if he refuses to leave, appear in court for an eviction hearing.

But only California has any laws protecting a renter in a foreclosure.
The owner does not have to tell you,

The only money to get back is the deposit and he can sue the landlord for that money.