Your morals are not dictated by others bad management or poor behavior. They are yours to control. It is property that does not belong to you.
Ideally, yes.
You are assuming it is possible to return. There may not be any practical way of returning the item if you don’t know who the liquidator is. It is not unlikely that the office space as well as the furniture was rented and there may not be much to sell. I imagine that the primary value would be in software created and there should be multiple copies
Also, if it is a computer that is over about 18 months old it has very little value. They may not want it.
I’d try to return the files. I’d send an email to someone as a CMA strategy and tell them I had the files and the laptop but if they wanted it back they’d need to tell me who to give it too and provide a receipt for proof I’d returned it.
If they didn’t reply I consider myself to have done due diligence and not worry about it.