The correct answer is C. 1978.
Chaudhary Devi Lal was the Chief Minister of Haryana from 1977 to 1980. During his tenure, he amended the Panchayat Act in 1978. The amendment increased the number of seats in the Panchayats and made it mandatory for women to be elected to one-third of the seats. It also introduced a system of reservation for Scheduled Castes and Scheduled Tribes.
The 1978 amendment was a major step forward in the development of Panchayati Raj in Haryana. It helped to make the Panchayats more representative and accountable to the people. It also helped to empower women and marginalized groups.
The other options are incorrect. Option A is incorrect because the Panchayat Act was not amended in 1970. Option B is incorrect because the Panchayat Act was not amended in 1994. Option D is incorrect because the Panchayat Act was not amended in 1964.