This is the raag Todi in Hindustani (north Indian classical) music. It takes the following notes in the ascent and descent:
Aroh: Sa, Komal Re, Komal Ga, Tivra Ma, Komal Dha, Shuddha Ni, Sa
Avaroh: Sa, Shuddha Ni, Komal Dha, Pa, Tivra Ma, Komal Ga, Komal Re, Sa
The closest equivalent raga in Carnatic (south Indian classical) music is the ragam ...
You can see that there is a percussion instrument on Zakir's left that looks like a thick book bound with a belt. What exactly is this instrument? Is it really just a book ?
Yes , it is just a thick book ! But again , it is not 'just' a book , but an Amplified book . He used this Amplified book as a Percussion instrument in several other concerts too .
According to Film Music Reporter, the composers are Alex Heffes and Anoushka Shankar. This is confirmed by Heffes's Wikipedia page (linked above) and Anoushka Shankar's Facebook page.
The website Soundtrack Mania lists the credited songs from season 1 and allows for listening.
Trailer: A Suitable Boy - Alex Heffes & Anoushka Shankar
Episode 1: Do Naina ...