Najafi Q&A: Waif

A brother gifted his married sister a ring and told her he was unsure whether it was gold or something else. She took it to the gold market, where they confirmed it was gold, so she sold it and spent the money. After a long time, her brother passed away, may Allah have mercy on him. The sister says her brother used to work in a restaurant on a travelers' road and had told her he found the ring in the women's restroom. She asks: is anything still owed by her brother, and how can she clear his liability? She mentions she does not remember the exact price of the ring but can estimate it?

After giving charity from lost property (waif), or any wealth of unknown ownership, or property whose owner was thought to be inaccessible, but then the owner is identified or the owner's identity is reached, is it obligatory to return the money to them?