Collocations for frightened - adj.

be, feel, look, seem, sound
become, get
I got frightened when he lost his temper.

extremely, fairly, very, etc.
badly, genuinely, terribly
almost
a little, slightly, etc.
suddenly

about
I was nervous and frightened about the future.

by
Most of us are frightened by our emotions.

of
I'm rather frightened of dogs.

frightened out of your wits, frightened to death (both informal)
She was frightened to death when she saw her small daughter on the edge of the cliff.

too frightened (of sb/sth) to do sth
My friend is too frightened of my father to come to our house.

Frightened is used with these nouns:
face, horse, squeak, whimper