My friends father and mother recently passed away, when her father died first she inherited the house, but her mother still lived there. When her mother passed away she went on to remortgage the house but was told she could do nothing with the house as her mother was declared bankrupt in 1994. The bankruptcy was 25,000 gbp and now my friend has been told she has to pay 75,000 gbp due to an 8% interest every year. If she can't do this the bankruptcy have the right to sell the house for as little as 80,000 gbp just to get there money back. What advice can you give her? Is she liable for her mothers bankruptcy 14 years ago?

Welcome to AMHD, where you can read, write, and enjoy a lot.
Who owned the house (how was it titled)? Did your friend's mother ever own the house? Who ("she") inherited the house?

Depends on the terms of that bankruptcy and the mother's ownership of the house as well the terms of the fathers will. There are a lot of questions here that need to be answered. I would suggest she may need a lawyer to straighten them out.