I'm sorry to hear about your dad. I would look into buying a Samsung Haven from eBay or Amazon. It's designed for seniors, with large buttons and display, loud sounds, etc. Be sure you buy one that works with Verizon and has a clean electronic serial number.
I'm very sorry to hear about your father. I hope he get better soon! We do have several great basic devices out there! My own father loves the Revere 2! Check it out here: http://www.verizonwireless.com/b2c/device/cell-phone/lg-revere-2
I hope this helps and your father beats cancer!
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I just noticed the LG Exalt may be a good choice for seniors. Check it out in basic phones.