When they head back to the gate, it isn't there.

They look for it. They ask the villagers if the gate does this regularly (nobody knew there was a gate there at all before this week) and if there's any known way to find it again (there isn't). They head to more towns and ask more questions about the gate. Nobody knows anything about it.

They're stuck in the Deep Plane.

Obviously this sucks. But it's not going to stop being the case just because it sucks.

She takes up sewing and farm work and practices her newfound magic enough to eventually be capable of providing magical cleaning services to people. She learns the local language. She admits to liking it here (it's certainly less inconvenient for her than for the Osirians), and to thinking that there's a chance that Asmodeus isn't actually powerful to take over the Deep Plane or maybe even all of the other planes. She forsakes his worship in favor of the local worship the dead god Ihys. She sews the eye of Aroden over the pentagrams on her clothes. She resolves to make her own destiny.

She writes fiction and poetry and histories of Golarion and takes care of her niece and does a lot of laundry and spends a lot of time talking to Hagan.