Nadigan
A man in desperate need of money decides to disguise himself as an old man to teach two young women. He falls in love with one of the them and simultaneously romances their guardian.
Starring Sathyaraj, Khushboo, Goundamani, Manorama, Venniradai Moorthy, Prathapa Chandran, Kundara Johny, Chinni Jayanth, Balambika, Karikalan
Watch "Nadigan" on Amazon Prime released in 1990. It's a drama and comedy movie, and has a rating of 6.9 out of 10 from Imdb which is usually fine for this kind of movie.