"Decline" and "deterioration" would indicate that Mother Teresa was working towards impoverished peoples' lives getting worse, which does not make sense. "Conservation" and "preservation" could work as they would indicate that Mother Teresa was protecting impoverished people. "Amelioration", meaning betterment makes the most sense.

Ridding her son of his "extroversion" would indicate that the mother wants to make her son less outgoing by making him join a football team, which does not make sense. "Mettle" means vigor of spirit, which is an attribute that joining the football team could probably strengthen, so that also does not make sense. "Assertiveness", or self-assurance, would also probably be strengthened by joining the football team. "Fatuity" is absurdity, which has nothing to do with constraint. "Diffidence", which means shyness, does make sense though.

"Loquacity," "exuberance," and "rambunctiousness" are all characteristics of loud people. "Intractability" would be used to describe someone stubborn, so that also does not make sense. "Docility," meaning yielding to authority, does make sense though.

"Probability," meaning likelihood, and "implausibility," meaning unlikelihood, do not make sense because the woes have already befallen the person's grandmother, so we would not be talking about them as uncertain events. "Dearth" and "scarcity" both mean lack of, which also does not make sense because the grandmother would not be complaining that she had not faced enough unfortunate events. "Plethora," meaning a lot of, makes much more sense. 

The daughter wishes to "spite" her mother because of her mother's feeling about "her new friends." Since she spites her mother by seeing them more, her mother must dislike her friends. "Disapprobation," meaning disapproval or condemnation, is the correct answer.

As his competitors would "never think of it," hiring art students is something peculiar and interesting for the subject of the sentence. The correct answer should mean a particular fondness for or inclination toward, the definition of "bent," when used as a noun.

The "humanitarian effort" wound up "harming some people," which indicates that it was not successful.   The correct answer will reflect the effort's failure and backfiring. "Debacle," meaning a disaster or complete failure, is the best choice.

The sentence notes the missing word indicates people who have an advantage over people who have never held a position before. The correct answer will mean the current holders of a job or title, the definition of "incumbents."

The sentence notes that critics believed the work was "derivative" and had "no originality."  The correct answer needs to reflect this borrowing and copying. "Pastiche," meaning a work of art cobbled together from many different sources, is the best answer choice.

So it is clear that this person is different from classmates, who are generally much better students. So "status quo" and "standard" do not make sense because they mean the norm. "Dupe" or "ignoramus," both used to describe someone foolish, might have worked, but there is no contextual evidence for this person being stupid. "Anomaly," which means deviation, is a much better choice.