My mother is probably waiting right now, wondering if I'll come.
Literal
Mother [topic-は] any-moment I [subject-が] come [question-か] [quotative-と] is-waiting [probably-だろう]
今にも = 'any moment now' — conveys imminence. 来るかと待っている = 'is waiting wondering whether (I) will come.' だろう adds the speaker's conjecture. か marks the embedded question within the waiting.