Mrs is female, so you need to use ‘she’, not he.
Seems is present tense, so you need to use ‘hears’ not heard, or
Heard is past tense, so you need to use ‘seemed’ not seems.
Very or quite or too are ok.
Much isn’t correct.
Mrs Morrison seems very / quite frightened when she hears that loud noise.
Mrs Morrison seemed very / quite frightened when she heard that loud noise.