The Ahmedabad Textile Labour Association (Majdoor Mahajan Sangh), the oldest union of textile workers in India, was founded by Mahatma Gandhi (option 1), making this the correct answer. Gandhi started this union during his stay in Ahmedabad, inspired by the plight of workers and his belief in trade unionism as a step towards swaraj (self-rule).

Option 2, Sardar Vallabhbhai Patel, although a significant figure in the Indian independence movement and a colleague of Gandhi, was not the founder of this association.

Option 3, N.M. Joshi, was an important trade unionist and social worker, but his involvement was primarily with the All India Trade Union Congress (AITUC) and not specifically with the Ahmedabad Textile Labour Association.

Lastly, J.B. Kripalani (option 4), was a politician and independence activist, however, he did not found the Ahmedabad Textile Labour Association.

Therefore, the correct answer remains Mahatma Gandhi.