The John Emms book is the most recent, and the move by move series offers a lot of explanation on each move.
Which Nimzo-Indian book to keep?

Emms gets a good review certainly... Nimzo is the sort of defence to study hard... otherwise stay away.

Thanks for the replies, everyone!
The review links were helpful. They even include a book by Emms on the scotch game that I obtained (I intend to transition out of the Scotch Gambit in my openings) - which makes me feel good about my choice. BUT, they make me want to keep both the Dearing AND the Emms book!
Okay. Keene will be given away, and I'll think about the others!

I have all 3 Nimzo books. I think both the Dearing (a repertoire book) and the Emms (an introductory overview) books are excellent. You can ditch the Keene book if you wish.
Chessable also offers a free Nimzo-Indian course (and many others)...
https://www.chessable.com/nimzo-indian-defense-tournament-edition/course/2359/
For a White opening repertoire, check out Vincent Moret's "My First Chess Opening Repertoire for White". It is based around 1.e4 and is excellent. Although the subtitle says "A Ready-to-go-Package for Ambitious Beginners" (it's an introductory treatment) I think the book's basic repertoire is suitable for players up to about 1700-1800 ELO.
See my commentary on the book in the following article...
Good Chess Openings Books for Beginners and Beyond...
https://www.chess.com/blog/RussBell/good-chess-openings-books-for-beginners-and-beyond
The book is also available in a Chessable version...
https://www.chessable.com/my-first-chess-opening-repertoire-for-white/course/7543/
https://www.youtube.com/results?search_query=my+first+chess+opening+repertoire+for+white
"… Note that Watson's series does not attempt to provide coverage of every opening, although it does treat the vast majority, in varying degrees. And of the openings it does deal with, there is no attempt to provide complete or comprehensive coverage. This series is more concerned with explicating ideas, themes and plans of the openings in general, and the analysis is impressive (IMO) for its depth and clarity. The author's point is not to cover the same ground that is detailed adequately and ad nauseum in the hundreds of other openings books which are concerned primarily with the 'theory' (i.e., the variations and lines) of specific openings. ..." - RussBell (June 5, 2018)
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-1-p3569.htm
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_1.pdf
"... I can strongly recommend Mastering The Chess Openings: Volume 2 to all chess players from 1800 on up." - IM John Donaldson
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-2-76p3570.htm
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_2.pdf
https://web.archive.org/web/20140627115737/http://www.chesscafe.com/text/hansen99.pdf
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-3-76p3571.htm
https://web.archive.org/web/20140626220240/http://www.chesscafe.com/text/hansen117.pdf
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_3.pdf
http://dev.jeremysilman.com/shop/pc/Mastering-the-Chess-Openings-Volume-4-76p3572.htm
"... This series is written in such a way that anyone rated from 1500 to 2400 will be able to benefit from it. ..." - FM Carsten Hansen (2010)
https://web.archive.org/web/20140627070808/http://www.chesscafe.com/text/hansen137.pdf
http://www.gambitbooks.com/pdfs/Mastering_the_Chess_Openings_volume_4.pdf

Emms' and Deering's books are both great, but aimed at quite different levels. You also have to bear in mind that Dearing's book is a repertoire book. For instance, one of the variations he recommends against the Rubinstein Variation, the Psakhis-Romanishin System (4.e3 b6 5.Ne2 c5) is an excellent choice. However, the replies at Black's disposal after 4.e3 is very wide indeed, and there might very well be other setups that would suit you better than this particular system which is quite unlike anything else in the Rubinstein.

Over the years, I've purchased 1, and been given 2 other books on the Nimzo-Indian. I'm really only going to have time to read one, and the rest I'll give away to the local youth chess club.
Which do you recommend I keep to read myself?
1) Winning with the Nimzo-Indian (Raymond Keene)
2) Play the Nimzo-Indian (Edward Dearing)
3) Nimzo-Indian: Move by Move (John Emms)
I'm a class C/B player, I play the Nimzo as black, but haven't studied it deeply yet (at least not enough to delve into an opening book beyond MCO/FCO).
Just wondering which book to keep to learn more about the opening. I don't think I need 3 books. Any opinions?
Thanks