There is no one booklist that can ensure to answer all questions in the examination. But yes, there are some books that can be considered sacred for UPSC, the ones that can ensure that at least 60% of the questions can be attempted after a good reading of them.
Polity by Laxmikanth
This book has been updated so frequently and has been made as comprehensive as possible by the Author. This is a definite buy and worth every penny spent.
For Ancient and Medieval Indian History, the good old NCERT seems to be reliable source. Its author is RS Sharma. Some chapters in the above even serve as a great source for Art and Culture section.
For Modern Indian History, Spectrum's Modern History and Bipin Chandra's Indian Struggle for Independence are great.
NCERTs of class 10th, 11th, and 12th are good starters to get a decent grasp over the discipline. However, this subject requires a supplement which can be in the form of any good coaching's class notes or any reputed publication's Geography Book for UPSC.
Apart from this, one has to invest in a good Atlas. Map work related to India and the World needs to be studied well by aspirants.
This is one subject where there is no good book available. Even the type of questions that can be asked cannot be ascertained.
For basic economics concepts, a reading of MICROECONOMICS and MACROECONOMICS from class 12th NCERTS can be undertaken. This can be substituted by class notes of any good coaching institute or Economics Book for UPSC Exam of any reputed publisher.
But, apart from the above, a good reading of the current year's Budget, Economic Survey, and reports of World Bank, IMF and the like which gets discussed by the Indian Parliament or media becomes relevant for the exam.
ENVIRONMENT AND ECOLOGY-
A very hot topic these days from the exam point of view. The best source of some basic concepts and matters of the discipline is Shankar's Environment Book. However, mostly questions are asked on areas which are in news so a good command over current affairs is the only way out. Do pay attention to the Red Book Data, Climate Change and related issues and the other burning global level environment damaging matters.
ART AND CULTURE-
The book I used was class 11th FIne Arts NCERT. Though, I agree that this a sketchy area and questions from this section are truly difficult. It also shows how Indian Educational System has somehow neglected our education in this regard that all of us find this portion difficult to attempt.
In the end, the above list is merely suggestive. It is possible that there may be even better sources available. I think knowing UPSC syllabus really well will be the only way that an aspirant can finally decide which book to buy and which one to leave!