Unlike most "deaths" in OP, this one was handled differently. She was stabbed with lethal intent, and she was shown reacting to the death blow, and her lifeless body was shown later in the chapter (the second to last page of Chapter 694, during Law's monologue). It also just makes sense writing-wise, because it's clear from how Oda wrote it that Monet is dead. Law's line of "Do unto others as they would do to you" is partly said in a panel where we are shown the lifeless body of Monet, who was about to kill everyone on the island right before she was killed herself.
Last night, me and my fellow admin were talking about Monet's survival. Then we felt sad just imagining how Oda would show us if she was actually dead.
Then this image came to me... of Doflamingo carrying a lifeless Monet... I just had to do it.
I apologize for the feels I am about to give..
From the site : arisakei.deviantart.com