Dad should have had access to Medicare, if he was old enough.
If not, there is that real, neat Affordable Care Act.
Otherwise, mom isn't responsible for most of dad's debts.
PA has a filial act.
http://www.timespub.com/2013/09/03/filial-support-act-alive-in-pa-2/
Be very careful, very careful, courts are incarcerating some individuals. Seek legal counsel, if gifts have been transferred.
Fortunately for mom, dad's debts were effectively extinguished upon his death, hopefully.
Mom can feel somewhat secure her pension is hers.
You can open dad's estate and properly advertise it.
That will start a one year statute for estate liability.
Mom at any rate, you would not be liable for the medical bills, which would primarily be a debt owed by dad's estate. Assuming, he has anything left.
One thing mom does not want to do is to remove assets of dad's estate for her own use.
She first wants to determine what are "estate" assets, as opposed to "tenancy by the entirety" assets, which would not pass to the estate.
It is probably not wise to make the determination on her own. You should have mother speak with an estate attorney to handle this, for her own protection, especially her pension.