Hey Allen, I understand the double loss. My MIL lives with us and has Alzheimer's. She also has a large amount of assets, but we're assuming it's going to take all of it to keep her going once she is no longer able to live with us. I hope you have lots of good photos and memories of your mom's good years, when she was still herself.
I have a few thoughts to share, and apologize if this sounds a little disjointed.
You know how people who are wallowing in debt think their life is going to be all unicorns and rainbows when their debt is paid off? Many think paying off the mortgage is going to be the same way. I'm here to tell you that it just ain't so. DH and I sold each of our houses after we were married to buy a single story house that was close to his work and a safe layout for his mom. We did well on both houses and chose to pay cash for our new one. It's been three years now and we both feel like we're missing something.
There is key information missing from your post. Namely your age(s) and how much you have saved for retirement. Also, the interest rate on your mortgage. So, let me pose a different question, assuming that you're relatively young and don't have as much saved as you'd like. Would you rather retire even earlier than you had planned or pay off your house now? Taking the lump sum and paying off the house just means you will have a paid-off house. Investing a lump sum now means that you have more money invested sooner, hence more and faster nest-egg growth. Solid investments with a long time horizon will earn you more money in the long run than paying off a fixed rate mortgage of relatively short duration. Investing instead of paying off the house (assuming fixed rate) over time allows your money to grow, while your mortgage outlay remains constant. When you hit your FI number, you will always have the option of paying off the house.
I promise you, on a scale of elation, hitting FI and being able to RE beats the pants off not having a mortgage. And yes, it is completely possible to FIRE with a mortgage. Hell, the mighty arebelspy even did it with outstanding student loans!
Hope this helps.