One Sister have I in our house -
And one a hedge away
There's only one recorded
But both belong to me
Dickinson is referring to her sister Lavinia, as opposed to her sister-in-law Susan Gilbert, mentioned in the next line. The “house” is the Dickinson Homestead or Dickinson House in Amherst, Massachusetts, now part of the Emily Dickinson Museum. 
 
 Whatever you call it, Emily didn’t leave it much.
One Sister have I in our house 14