If they fail to keep you safe, well there is nothing you (or your estate) can do about it.
If you live in an area where the state has also said you can't defend yourself (or you can't have effective means of self-defense) you are SOL.
The judge said a public entity cannot be sued when employees fail to perform their jobs.People don't like to believe this, but they should review Castle Rock vs. Gonzales case decided by SCOTUS last year.
One of the consequences of the Castle Rock case is that if you are going to be defended, it is you who is going to have to do the defending. (Feminists hate this - it is the opposite of being a victim.)
Self-defense is a human right. Having the police defend you is not.