In Act Four, although there are no lines spoken by any person condemned to die that day other than John Proctor and Rebecca Nurse, it stands to reason that both Mary Easty and Martha Corey are also going to be hanged that morning.
When John is trying to decide whether to lie, confess, and save his own life or to continue to refuse to confess and die that day, he says to Elizabeth, "Let them that never lied die now to keep their souls." In so saying, he makes it sound as though he knows that others will hang too. Even more persuasive is that these are the names Danforth asks Proctor about when he questions Proctor during his confession. Danforth asks, "When the Devil came to you did you see Rebecca Nurse in his company?" John says no. Danforth asks if he ever saw her sister, Mary Easty in the Devil's company; John says no. Finally, Danforth asks if he saw Martha Corey with the Devil; John says no. He is unwilling to implicate anyone else even though it makes Danforth fail to believe that he's telling the truth. However, because we know for a fact that Rebecca will hang today, it makes it seem as though Danforth is trying to get Proctor to cry out on anyone else who is condemned to die that morning to make the hangings seem as justifiable as possible to the town.