I am sympathetic to your situation, but it is Forum Rule that you show you have attempted the question.
Having done everything in your power to complete the assignment, I presume you have found at least one interesting molecule for the assignment - can you share what you have found so far?
Probably the best way to approach this is to search for the application. For example, a major application might be "antibiotics", search for "antibiotic drugs", find a drug, look at the structure and figure out which structural category from the assignment it fits in (likely more than one).
What other important applications can you think of?
One approach is to look around you. What substances do you use or consume in your daily life? Find out what these things are made of.