。
She should have finished her homework by now.
Literal
She [topic-は] homework [object-を] finished [completion-てしまった] [should be-はずだ].
Two grammar points layer here: ~てしまう marks the homework as fully completed (its 'completion' sense rather than 'regret'), and ~はずだ adds the speaker's expectation that this completion should be the case. Together, 終えてしまったはずだ = 'should have finished (completely).' The speaker expects the homework to be done based on what they know about the situation.