I was served a 3 day pay or quit in CA. She is losing the house... going to auction in 5 days.. She wants to enter the home in 24 hrs. What do I do?

Who wants to enter the home in 24 hours ?

So have you not been paying rent ? You can be evicted even if home is in stages of foreclosure if you don't pay your rent.
The lease or rental agreement is valid till the day it sells.

With notice, she can enter the home anytime she wants.

Let her in the home.
Also understand that many people will be coming by to look at the home and walking around the home prior to the auction.

If the home really sales in 3 days, you can just stay for now, since she can't evict you, if the home does sale.
If of course she gets the sale put back, she can have you thrown out by eviction though the courts.