He's a lesser known music director and vocalist. One of his most popular songs is perhaps the Lata number called "Guzra Hua Zamana Aata Nahin Dobara" from 1956 film Shirin Farhad.
Full name: Mohinder Singh Sarna, and he was born in the year 1925 (on 24 February 1925).

Wikipedia page: https://en.wikipedia.org/wiki/S._Mohinder

Songs of Yore, popular blog pays tribute to him: https://www.songsofyore.com/best-songs-of-s-mohinder/

Not all of his films seems to be listed on IMDB.
for example:
Link
https://www.songsofyore.com/best-songs-of-s-mohinder/
mentions film Zammen Ke Taare (famous/ my fav song in childhood: 'Ae Mere Pyaaro, Zamin Ke Taaro, Jaana Tumhe Hai Kahan' but is not listed in IMDB.

Ramesh Deo (born in 1926, said by Wikipedia; and according to IMDb was born in 1929).

Found this link that lists present Bollywood Actors 70+
https://www.indiaeinfo.com/bollywoods-o ... rossed-70/

Bollywood’s Old Actors And Actress Who Crossed 70+ Age
February 15, 2021 Admin

There are many actor and actresses of Bollywood who crossed their 70 years but still working well in movies and society. Here is list of those Bollywood’s alive stars who crossed age of 70 year . They are icon of Indian cinema. God! give them long and healthy life.

Mr. Chandrashekhar G. Vaidya (DOB- July 07, 1922) – 98 Years
Mr. Dilip Kumar (DOB- December 11, 1922) – 98 Years
Mrs. Mumtaz Begum (DOB – April 7, 1923) – 98 Years
Mrs. Kamini Kaushal (DOB- January 16, 1927) – 94 Years
Mr. Ramesh Deo (DOB- January 30, 1929) – 92 Years
Mr. Gulzar (Director, DOB- August 18, 1929) – 91 Years
Ms. Lata Mangeshkar (Playback Singer, DOB- September 28, 1929) – 91 Years
Mr. Rajkumar Kohli (Producer, Director, DOB – September, 14, 1930) – 90 Years
Mrs. Kalpana Kartik (DOB – September 19, 1931) – 89 Years
Mr. Anandji Virji Shah (DOB – March 2, 1933) – 88 Years
Mrs. Asha Bhonsle (Playback Singer, DOB- September 8, 1933) – 87 Years
Mr. Madhavan Nair (Madhu) (DOB – September, 23, 1933) – 87 Years
Mr. Achyut Potdar (DOB – August 22, 1934) – 86 Years
Mr. Shyam Benegal (DOB – 14 December, 1934) – 86 Years
Mrs. Supriya Devi (DOB- January 8, 1935) – 86 Years
Mr. Ravi Tandon (Film Director, DOB – February 17, 1935) – 86 Years
Mr. Prem Chopra (DOB- September 23, 1935) – 85 Years
Mr. Salim Khan (Writer, 24 November 1935) – 85 Years
Mr. Dharmendra (DOB – December 8, 1935) – 85 Years
Mrs. Waheeda Rehman (DOB – May 14, 1936) – 84 Years
Mrs. Shushma Seth (DOB- June 20, 1936) – 84 Years
Mrs. Vyjayanthimala (DOB- August 13, 1936) – 84 Years
Mrs. Mala Sinha (DOB)- November 11, 1936) – 84 Years
Mr. Biswajit Deb Chatterjee (DOB- December 14, 1936) – 84 Years
Mr. Manoj Kumar (DOB – July 24, 1937) – 83 Years
Mr. Birbal (DOB – October, 28, 1938) – 82 Years
Mr. Arvind Trivedi (DOB – November 8, 1938) – 82 Years
Mr. Ram Sethi (November 15, 1983) – 82 Years
Mrs. Helen (DOB – November 21, 1939) – 81 Years
Mr. Bharat Kapoor (DOB – January 01, 1940) – 81 Years
Mr. K.J. Yesudas (Singer) (DOB- January 10, 1940)- 81 Years
Mrs. Shubha Khote (DOB- 20 March, 1940)- 81 Years
Mr. Govind Nihalani (Film Director, DOB – 19 August 1940)- 80 Years
Mr. Vikram Gokhale (DOB- October 30, 1940) – 80 Years
Mr. Asrani (DOB- January 1, 1941) – 80 Years
Mr. Sanjay Khan (DOB- January 3, 1941) – 80 Years
Mr. Roshan Seth (DOB – April 2, 1942) – 80 Years

The list seems credible enough, except for the fact that they've listed Supriya Choudhary; who passed away in 2018. (if it is the Meghe Dhaka Tara actress in question; who also starred in Aap Ki Parchhaiyan with Dharmendra.)