Best Answer Explained in Below-:

In the question, we need to determine which pair of words are synonymous, meaning they share a similar or identical meaning.

Let's analyze the options provided:

A) **দাস - ঝি**: "দাস" refers to a male servant, and "ঝি" refers to a female domestic worker, usually for household chores. Hence, these words describe different roles and are not synonyms.

B) **সম্মার্জনী - শতমুখী**: “সম্মার্জনী” refers to something that is respectable or connects with honor, while “শতমুখী” can mean having multiple faces or perspectives, but it is also used in contexts related to the honorific or respectability aspects, particularly when discussing complex matters. In this context, these terms reflect similar notions of dignity and respect.

C) **নীহার - নীড়**: “নীহার” means mist or haze, while “নীড়” translates to a nest or abode. These words contextually relate to different natural phenomena and are not synonyms.

D) **দুর্বলভুজা - হতভাগ্য**: “দুর্বলভুজা” means weak or ineffective, while “হতভাগ্য” means unfortunate or unlucky. Again, these words describe different states and are not synonymous.

Upon evaluation, choice B emerges as the best option as "সম্মার্জনী" and "শতমুখী" can both relate to concepts surrounding dignity and respect, aligning them closer as synonyms compared to the other options. Thus, **B is the correct answer**.