You should sit down with your agent & their broker to review the marketing of your property. What the current price is, what comparable properties are selling for & the feedback from any showings. You might also want to speak to an attorney & your broker about exploring a short sale position. Unfortunatly properties are taking a bit longer to sell in many markets.
You should sit down with an attorney to review your situation & how the house was passed to you and your specific rights. You may end up having to find her a place to go and pay for her move this is called "cash for keys" but before you attempt this an attorney can best advise you.