Which Robert Frost poem discusses being in the world and in your home alone when a knock comes to the door?

I am trying to find theRobert Frost poem that discusses someone being alone in the world and being home alone when one day theres a knock at the door. The poem leaves you questioning who it could be, is it death? is it a ghost? etc. i am looking for this poem to writea paper on but cant remember the title, its been years. can anyone help?