A young girl’s from Lucknow had invoked the RTI act to know as to who conferred the title of “The Father of the Nation" on Mahatma Gandhi and when.
Newspaper Report
I don’t think the title had to be bestowed on Gandhi; the people of that time called him Bapu, and he accepted that with all his humility and signed innumerable letters as Bapu.
I can think of two instances from history that may add some light:
On October 2, 1944 Mahatma Gandhi turned 75. He had shifted to Sevagram after his release from Yeravda Prison in April 1944 in the aftermath of his 'Quit India' movement. His 75th birthday was celebrated all over the world. Netaji Subash Chandra Bose, Commander-in-Chief of Azad Hind, performed a flag hoisting ceremony in Rangoon, Burma ( Yangon, Myanmar) and broadcasted a message through the Azad Hind Radio " Father of our nation! In this holy war for India's liberation, we ask for your blessings". This is the first recorded and known instance when Mahatma Gandhi was addressed as the "Father of the Nation".
On the night of 30 January 1948, the day Mahatma Gandhi was assassinated, Pandit Jawaharlal Nehru in a broadcast to the Nation and to the world referred to him as being commonly called as the 'Father of the nation."
Excerpts "Friends and Comrades, the light has gone out of our lives and there is darkness everywhere. I do not know what to tell you and how to say it. Our beloved leader, Bapu as we call him, the Father of the Nation, is no more. Perhaps I am wrong to say that. Nevertheless, we will not see him again as we have seen him for these many years. We will not run to him for advice and seek solace from him, and that is a terrible blow, not to me only but to millions and millions of this country."
Pandit Jawaharlal Nehru's broadcast