When does the tenure of an executor cease?

My mother passed in 1986. I was the executor of her will. My dad had passed in 1969. Her will said that her two daughter and son(me) would share equally in the division of the assets. One daughter has since passed.
An award for work environment caused death is being awarded . Do I still have an executor capacity to disburse the funds? Does my deceased sister's family have any claim to the award? Are there any tax implications?
I know what to do ethically; its the legal issues that concern me!