Mother got a letter from a lawfirm.

Hi, well a long story short, maybe more than 8 years ago my mother had sears account, it was around 4,000 dollars I believe, and just a few days ago I checked her mail to see that she got a letter from some law office stating that they owned upwards of 20,000 dollars and that she had to pay it or else they will file suit. Now, my moms only receives ssi, she has no assets, she no longer works. Anyways, I basically pay to take care of her, my question is, could they stop her from getting benefits from the government ? Also, if a judgement is filed against her, how are they going to collect if she has no big ticket items to start with ? Also, could they somehow attach the debt to me ? Anyways, thanks for your time.