can we say it is enigma? like it is difficult to understand her success? any suggestions, inputs??

Enigma means riddle or conundrum.

However, the dilemma or fork in the road she should deal with was the fact that at the pinnacle of her career she was stripped of the subject or field of study where she was engaged.

I.E., just when she achieved a great result, she had the dilemma how to do at that moment of how to move forward, considering that the area where she had competence was stripped from her.

I hope now is clear.

A tricky one as sentence

Carcass

Hello Sir,

wonder if we might take a look at this question again concerning dilemma vs. enigma.

IMO(and likely wrong), Dilemma is a situation where one must choose between two (or more) specific, usually unpleasant, option - however, the sentence does not tells us what those two options are. It doesn't say she had to choose between "retiring in glory" or "restarting in a new field."

As for Enigma, it can mean the Irony of Timing and "riddle" of fate. The phrase "at the very moment when" is the clue in the sentence.

The fact that these two opposite things—the peak of her power and the total emptiness of her cupboard (bereft)—happened at the exact same time is what makes it a puzzle, mystery, or enigma. It’s a "riddle" of fate rather than a "choice" she has to make.

Wonder if you might take your look? Thanks in advance, Sir

The best fit is C. epitome and D. bereft. The sentence means her career reached its peak/ideal example at the moment she was lacking a compelling subject, and epitome means an ideal or typical example while bereft of means lacking something.