The profile for Guy Smith shows that he died prior to 10 Jan 1781 when his will apparently was offered for probate. The source isn't really clear as to whether that is date the will was proven or something else.
Anne Hopkins Smith profile gives a date of death for as after 10 Jan 1781. Indicating she was listed in the will of her husband and survived him. Both dates are approximate, but they didn't die on the same day.