。
I imagine she's trusted by everyone.
Literal
She [topic-は] anyone [from-からも] is-trusted [probably-のでしょう].
誰からも uses the source-marking から rather than the more common dative に for the passive agent. Both work with 信用される ('be trusted'), but から foregrounds the trust as flowing from a source: trust comes from each person and lands on her. ~のでしょう adds soft conjecture without changing the basic claim — explanatory の (treating the trustedness as observable fact) plus でしょう (giving it the speaker's slight hedge). Slightly polished and reflective in feel, the kind of remark made aloud after watching someone interact with a group.