。
She might not be home right now.
Literal
She [topic-は] now home [at-に] is-not [might-かもしれない].
Plain-form negation いない attaches directly to ~かもしれない without a copula — verbs and i-adjectives plug straight into かもしれない. Only nouns and na-adjectives need the bare form (静かかもしれない, not 静かだかもしれない). Compare with the flat negative いません ('isn't home'): the difference is one of speaker certainty, and かもしれない adds just enough doubt to keep the statement open.