What are some specific examples in the book of moral ambiguity in A Passage to India?

One instance of moral ambiguity concerns the Caves and the
events that happened in them.  Forster gives little in way of clarity as to what
happened in the Caves between Azis and Quested.  Due to this fact, there is moral
ambiguity surrounding it because judgments are impossible to make.  The idea of the
Caves' ambiguity is fed by the aspect of "BOUM," the sound made inside the caves. 
Inside the cave is total darkness, where all individuals are reduced to nothing more
than "BOUM" and all sounds are reduced to no more than "BOUM."  In this reductive light,
ambiguity is present because in a setting that is strictly defined by cultural contexts
and specific social constructs, the result of the Caves reduces everything to a singular
element.  This is ambiguous because it is a very strong repudiation of social practice. 
When Mrs. Moore comments that there is little, if any, difference between love in a
church or love in a cave, she is revealing the level of moral ambiguity present in the
British experience in India.  The echo in the cave that results in "Everything exists,
nothing has value," only adds to this moral ambiguity present.