I have dealt with this exact issue. Be forward (and kind. that goes a long way) and approach them with an offer for the domain, social, and any databases they might have that might be useful. They may not be able to sell anything because of the conditions of the bankruptcy. However there are some clauses that allow the owner to sell data and the domain. If you can get those at a reasonable price do it. Redirect the URL. Put out a press release about what has happened and how it's sad to see a closure of the company and say that you are now here to meet the needs. Use SEO keywords in the press release. Then send something similar to the email list and through social that you acquire. Connect with their customer base in a kind and considerate way. Any other questions let me know Good luck!