Answer:
To keep suspicion from falling on her and her husband, Lady Macbeth smears Duncan's blood on his two sleeping bodyguards.
Explanation:
In Act I scene 7 of Macbeth, it is Lady Macbeth who plans to put the blame for Duncan's murder upon his two chamberlains who will be in his bedroom while he sleeps in order to protect him. To do so, she smears Duncan's blood on the two sleeping bodyguards so that they will be naturally linked to the murder once the body is found.
