Give house back to mortgage holder?

What are the personal risks my mother in FL would run if she signs a quitclaim deed and gives her house back to the bank rather than pay mortgage? She has purchased another home to move to and may lose money if she sells the FL house with realtor commissions, etc. She also has an equity line on the house, which she assumes would simply get paid off when the bank sells the house.
Would she likey be sued or incur other serious consequences? House value should just about cover both loans...will be close. She is not worried about her credit, she is elderly and will not need more loans.

[HomeGuru]

If I was the lender I would say, no way, I'm not taking the property. I will foreclose on the property, get a judgement and place a lien on the new house. Then I would foreclose on the new house. So if you are not concerned about your credit about being concerned over being homeless.