In Macbeth successful were the murderers?

No, the murderers were not successful. While they did manage to kill King Duncan, their actions ultimately led to Macbeth's downfall. Duncan's sons, Malcolm and Donalbain, fled to England after their father's murder, and Malcolm later returned with an army to overthrow Macbeth. Macbeth also began to suffer from paranoia and guilt after the murder, and his mental state continued to deteriorate as his reign proceeded. He eventually descended into madness and was killed by Macduff in battle. Therefore, despite their initial success in killing Duncan, the murderers could not ultimately be considered successful, as their actions directly led to Macbeth's demise.