The most common cause of laryngeal stridor in a 60 year old male is -
Most common cause for stridor in 60 years old male will be carcinoma larynx as carcinoma larynx occurs in males (predominantly) at the age of 40–70 years.
Most common and earliest symptom of subglottic cancer is stridor.
NOTE:

Nasopharyngeal cancer does not lead to stridor
Thyroid cancer causes stridor rarely
Foreign body aspiration is a common cause of stridor in children and not adults.
Nasopharyngeal carcinoma
Thyroid carcinoma
Foreign body aspiration
Carcinoma larynx