。
She wanted to help them.
Literal
She [topic-は] them [object-を] wanted-to-help.
Standard ~たい construction in past form: 助けたい ('want to help') → 助けたかった (past, 'wanted to help'). Note how ~たい inflects like an i-adjective (~たい → ~たくない → ~たかった → ~たくなかった). One pitfall: ~たい is normally restricted to first-person desires, but in past tense it can describe a remembered past wish — including the speaker's own past, or a third-person's reported wish.