Which of the following films won the 'Best Film on Other Social Issues' Award…

The National Film Awards are India's apex state-conferred film honours, given out every year across many separate categories — Best Feature Film, acting awards, technical/craft awards, and a feature-film category recognising a film that engages meaningfully with a social issue, called 'Best Film on Other Social Issues'. (A separate, now-discontinued non-feature-film category was historically called 'Best Film on Social Issues' — the two are not the same award.) Each award at a given edition belongs to exactly one category, so identifying the winner means matching the FILM to its SPECIFIC category, not just to the ceremony or year.

At the 65th National Film Awards (announced in April 2018, honouring films certified in 2017), the Malayalam film Aalorukkam, directed by V. C. Abhilash, won the Best Film on Other Social Issues award. The film follows an Ottan Thullal exponent who searches for his missing son and must then confront his own prejudice to accept that his child now lives as a transgender woman.

• Village Rockstars (Assamese) was honoured at the very same 65th National Film Awards — but with Best Feature Film, the top overall honour, not the Best Film on Other Social Issues award.

• Nagarkirtan (Bengali) had its lead performer honoured at the same ceremony with Best Actor — a performance award, not the Best Film on Other Social Issues award.

• Toilet: Ek Prem Katha (Hindi) received the Best Choreography award at the same ceremony — a technical/craft honour, not the Best Film on Other Social Issues award.

So although all four films were honoured at the 65th National Film Awards, only Aalorukkam's award matches the specific Best Film on Other Social Issues category asked about here.