Final answer:
Mme. Loisel's state of mind at the beginning of the story is best described as 'discontent.' Her covetous thoughts about a luxurious life she does not have drive the story forward, highlighting the story's moral lessons on vanity and materialism.
Step-by-step explanation:
The emotion that best describes Mme. Loisel's state of mind at the beginning of the story is c) Discontent. This can be seen as she often dreams of a more luxurious life than the one she currently has. Ruminating over her lack of wealthy possessions and grandiose lifestyle, Mme. Loisel covets an existence filled with the finery and status she does not possess. This discontent propels her into making choices which lead to the significant consequences she faces later in the story, including years of hard labor to replace a lost necklace which, unbeknownst to her, was not made of real diamonds. Moreover, her dissatisfaction with her situation is a critical component of the story's moral about the dangers of vanity and materialism. Thus, it is an essential part of understanding her character and the overarching themes of the narrative.