The lady shouted with a loud, shrill voice.

Answer: Option C

Shrill : (of a voice or sound) high-pitched and piercing.
Feeble : lacking physical strength, especially as a result of age or illness.
Blunt : (of a cutting implement) not having a sharp edge or point.
Muffled : (of a sound) not loud because of being obstructed in some way; muted.
Inaudible : unable to be heard.

Antonym of Shrill is Muffled