There is a mention that Hanuman while in Lanka anticipates Seeta to visit river bank to perform Sandhya vandanam
Can someone post the reference? Either of the above scenarios.
As per Valmiki Ramayana: Sundara Kanda - Sarga 14,
While searching for Sita in Lanka, Hanuma enters the Ashoka garden. He starts looking for Seetha in the garden. At the end, He thinks that Seetha would definitely come to that river [in Ashoka garden] for Sandhya rite if she were to be alive:
संध्या काल मनाः श्यामा ध्रुवम् एष्यति जानकी |
नदीम् च इमाम् शिव जलाम् संध्या अर्थे वर वर्णिनी || ५-१४-४९
[Hanuman:] The ever youthful one with the best complexion, Seetha interested in the rites of Sandhya time will definitely come to this river with the auspicious water for Sandhya rite. ~Source