She needs to see a solicitor. As the mortgage company might have a problem with her being taken off the mortgage, she might need to go to court, to get her name removed. If there is a current problem with the mortgage repayments, with the possibility of a debt being left behind, if the house is subject to repossession, the mortgage company might not be willing to remove her. She is still subject to the mortgage contract and therefore is responsible for any debt, jointly with her ex. As the circumstances have changed, there may be some form of court process that enables her to be removed from the mortgage contract.
It might cost your friend a bit in legal fees, but if the house is repossessed and then sold at auction, there could be a debt of many thousands.
It may be a good idea for your friend to get hold of her credit report to see what loans are against her name. If there are other debts, then she might also want to get advice about them as well.
Many solicitors will provide an initial half hours consultation free of charge and her local citizens advice many have details.