Mother in law does not have Medicare, what do we need to know?

We’re in Texas. My family moved in with my mother in law 6 years ago. Husband is her only child. I take care of her (she’s 86, disabled, so I cook, clean, run errands) but she doesn’t need nursing type care yet. Years ago she put hubby on her bank account but she still manages all her finances. She has a living will. My main concern is if she ever needs skilled nursing care. She doesn’t have Medicare because she never paid into SS. She’s a retired school teacher and has retirement and lifetime health insurance. Because this home is our only primary residence, if she were to need nursing home care beyond what I am able to provide, how will that work? She doesn’t have a lot of money set aside, but I assume nursing home care costs would come from that until depleted. Then any remaining balance would come from this house? In the form of a lien? Our names are not on the deed. Should we do that in order to protect our rights to this house?