I have an elderly parent that is going into a nursery home,and they will be taking all her SS money that she used to pay bills

I recommend you seek the advice of an estate planning and elder law attorney. Your mother's interest in the house has a value. This value can be attached by Masshealth and Medicare to offset the cost of her care at the nursing home.
In addition, your question doesn't say whether your mother received Masshealth. I would seek the advice of someone who can look at your mother's whole financial picture, find a way to protect her interest in the house, and keep her receiving the care she needs.

The previous poster is correct, you should consult with an elder law attorney. In this instance they will want to know how that property is actually owned and under what circumstances did your mother obtain a 1/3 interest in the home. If that home was just transferred into two other persons name within the last few years, then you may have a penalty period issue to deal.

You also may have certain exemptions that you could use to help protect the house. For instance, the is an exception that will allow your mother to transfer the home to a caregiver child if that child lived in the home for a period of two years and delayed your mother's need to go into a nursing home.

The key is understanding the rights and options available to you under MA. law and that means you will want to speak to an Elder Law attorney in MA.