Are we responsible for paying debts after mom's death?

My friend's 94 year old mom died a couple of weeks ago. It's been rough, but it was as best as possible. She died in our home, in bed, with almost no pain or distress - and surrounded by people who loved her.

And now... dealing with the details after. We needed every penny of her small income for care and went into debt for extras - including funeral expenses. There are a couple of bills that have come in afterwards for transport services that insurance did not cover.

I know if there was money or assets in her estate, that the outstanding bills would come out of that - but there is no money in her estate.

My friend was the POA and signer on her mother's checking account. Is she responsible personally for paying these bills out of her own pocket? Or can she inform the company of the death and the lack of any funds and just let it go?

This topic may have already been addressed, but I couldn't find the info. Any info, links, etc. would be helpful.

thank you.