Remove “a”. We say “It is ten minutes to six.” You don’t use an article before the number of minutes in this context.
Should be “a necklace.” Necklace is a countable noun, so it needs an article.
Should be “the effort.” The effort is specific to the nurses, so it needs “the.”
Remove “a.” We say “by bus,” “by car,” or “by train” (Mode of transport + no article)
Should be “on the night.” Since we are talking about a specific night (the night of the robbery), the definite article “the” is required.
Should be “a little water.” “Little” means almost nothing; “a little” means some. She couldn’t give it to the child if there was “little” (none).
Should be “the credit.” Credit is being specified as belonging to the leader, requiring “the.”
Remove “the.” If he goes for prayer (primary purpose), we say “go to church.”
No error. (Note: “Audience” can take a plural verb “realize” when referring to the individuals within the group).
Should be “The Indian people.” “Peoples” usually refers to different ethnic groups or nations; “people” is the plural of persons within a nation.