I do a LOT of tech work for older people and I have learned a few things over the last few years of tablets taking off.
1. It doesn't matter what OS they start on, it will become the one they understand if they haven't used one before. I've had several customers that started with apple products that cant figure out android and just as many the other way around. Even if you weren't forced into it with the price point I would go android for savings now AND later.
2. Screen size matters, with most older folks the bigger the better. I get two complaints about 7" tablets #1 "I can't see the little stuff on the screen"
3. and #2 is users of many of the "cheap" 7" tablets have performance complaints when browsing their favorite websites.
That Nextbook 8" honestly looks like a very good choice for the money or as mentioned above the Kindle Fire HD is a good device to consider and it has a more basic UI out of the box that may be a pro or a con.
i7-4770K/ASUS Z87-K/16GB ADATA/128GB Sandisk X110/3TB/GTX 770/Rosewill Capstone 750-M (main rig)
i5-3570K/GA-Z77X-UD5H/16GB Team Vulcan/120GB OCZ Solid 3 SSD/2 x 1TB/1.5TB/320GB/GTX 670/Rosewill Capstone 750-M (secondary location main rig)
i7-4700MQ/MSI GT60 2OD-026US/16GB/128GB mSATA/1TB/GTX 780M/180W AC Adapter w/9 cell battery (gaming laptop)
E8400/GA-EP45-UD3P/2GB Ballistix PC2-5300/3TB/2 x 2TB/2 x 320GB RAID 1/250GB/8600GT/Antec BP550 (server)
Q6600/EVGA 122-CK-NF68-T1/4GB PC2-8000/2TB/2 x 1TB/500GB/9600GSO/500W(work rig)