It's the CPS equivalent of "let me in your house or else I'll get a search warrant and things will go worse for you." If they had the evidence to get in the house, they wouldn't be standing there asking you, the police would be there with battering rams busting in.

It's a bluff. If there is actually evidence they need to remove the child they will go get the order from the judge and execute it. And if that evidence exists, in no way would anyone in their right mind let you keep the kid by signing a "safety plan" to pretty please keep grandma and grandma around, who are not in any way credentialled/vetted to host supervised visitation.