Whose responsibility is it to ensure children, particularly of the disadvantaged groups, are not discriminated against?

Legally, of the appropriate governments, local authorities and the schools; monitored by the SMCs, civil society groups and the NCPCR/SCPCRs. Model Rule 5, (3) and (4) explains this in clear terms:

 

(3) The State government/local authority shall ensure that no child is subjected to caste, class, religious or gender abuse in the school.

 

(4) For the purposes of clause (c) of section 8 and clause (c) of section 9, the State

Government and the Local Authority shall ensure that a child belonging to a weaker section and a child belonging to disadvantaged group is not segregated or discriminated against in the classroom, during mid day meals, in the play grounds, in the use of common drinking water and toilet facilities, and in the cleaning of toilets or classrooms.