How do I get a value on property?

One way to get the value is to order an appraisal. The best way is to connect with a local agent that can assess the value, prepare a comparative market analysis and recommend a price. This will include recent sales of properties with similar features so you can determine what buyers are willing to pay for it.

Find a local Realtor you and your mother agree to work with and have that agent work up a market analysis. This will include comparable sold and active on market properties so that you can see what similar properties have sold for and are on market for at present. You can pay for an appraisal as well but it may not be necessary, since your local Realtor should have current market data. If the property is super unique and comparable properties are hard to find or non existent then the appraisal my be the way to go.