Final answer:
Emilia agrees to help Cassio with an unknown task or objective in a literary work.
Step-by-step explanation:
In the given context, the subject refers to a literary work, possibly a play or a novel, where Emilia agrees to help Cassio with a certain task or objective. Without more specific information, it is difficult to determine the exact nature of their agreement. For a more accurate answer, knowing the title and author of the literary work would be helpful.