My father was in the military and has a DD214. Is he a Veteran? And does he quilify for benefits?

Pokey, I am not familiar with military benefits, but I did find articles here on Aging Care that I hope can help point you in the right direction:

https://www.agingcare.com/veterans-assistance

DD214 if the gate-opener. Then it comes down to combat vs no combat zone duty and income/asset level. The VA has a website and there is a link at the bottom of this page about veteran's benefits.

Even if his income is too high, if his dementia is advanced, he will qualify as Class 4, 'Catastrophically Disabled Veteran.'

Call your local VA dept. Set up an appt with their rep. Take all your Dads records. If he served during a war, he may be able to get Aids and Attendance.