Have your parents asked TWC/Spectrum about their 30/5 $14.99 plan? I have it for our Adirondack cottage, and my daughter was offered it when she said she was dropping cable completely, including Internet. The plan includes a free non-WiFi modem, although I preferred using my own.
Yes, I had them ask. Apparently they do not qualify? They can't threaten to leave because there is nowhere to go. Frontier isn't even selling internet in their village any more.