In a certain code language, 'nu vu du' is written as 'Please ask Hamza', 'hu du ru' is written as 'Give water please', and 'tu vu ru' is written as 'Give Hamza Book'. What is the code for the word 'Book' in that language?

tu

Given; In a certain code language, 'nu vu du' is written as 'Please ask Hamza', 'hu du ru' is written as 'Give water please', and 'tu vu ru' is written as 'Give Hamza Book'. 

So,

Comparing 1st and 3rd lines;

nu   vu   du  =  please  ask  hamza

tu   vu  ru  =  give  hamza  book

Now,

Comparing 1st and 2nd lines;

hu   du   ru  =  give  water  please

tu   vu   ru  =  give  hamza  book

Thus, in line 3 the only is left is book and only code is left is tu

Thus, the book is coded as tu.