Option (a.), 'To come to compromise with someone',refers to reaching an agreement with someone over something that was previously a source of contention.
Therefore, option (a.) is wrong because it doesn't indicate anyone being abandoned in a very tough situation.
> Option (b.), ‘Constant source of annoyance to someone', refers to continually being the explanation of annoyance to somebody.
Therefore, option (b.) is wrong because it doesn't indicate anyone being abandoned in an exceedingly tough situation.
> Option (c.), ‘To put someone at ease', refers to relieving someone of anxiety or stress and allowing them to unwind.
Therefore, option (c.) is inaccurate because it doesn't indicate anyone being abandoned during a tough situation.
> Option (d.), ‘To desert someone in his/her difficulties', refers to leaving/abandoning someone once they are in an exceedingly tough position.
Therefore, option (d.) is correct.