See No Evil (aka Blind Terror, 1971, U.K.)

Mia Farrow stars as Sarah, a blind young woman who goes to live in the English countryside with relatives.  A crazed killer slaughters her family while she’s away, reuniting with an old flame.  Due to her blindness, Sarah has no idea what has happened to them and sleeps in their home, none the wiser.

However, the killer’s not done yet.  Sarah must find a way to escape him or face the same fate.