Thank you so much for this post. Death is complex and I'm really happy you could be there for your grandmother during her struggle at the end of life.I don't remember the rules on the site for posting like, links to purchases, but I got a pretty decent mic for myself and even a friend for about $50 or under. It's not like, super amazing omg HD mic, but its not crackley or staticky, has a gain dial, and seems to not distort the sound/tone much. I can try to find it again and send you the link if you want!
As for recording JUST sound. Audacity might be the way to go. It let's you record and edit sounds from your mic and is completely free.
Earlier this year I lost my grandmother who was struggling with dementia, and she had had a music therapist come in a lot and even though she wasnt ever a music person, it really helped both her and us. I was a primary care giver for her in her last year and a half of life. I can safely say getting old is no joke. And will be the hardest thing anyone can or will ever do in life. Because of these experiences, I try to do whatever I can for those going through similar experiences. I hope you and your mother in law have many good years left together, and I hope that I have helped in some way.
I'll have to look into them. Things are looking pretty good as of late. She had some heart issues which have cleared up and her heart doctor said that her heart was beating stronger than ever. Odd enough this makes her much more aware of what's going on around her and a lot less agitated. 
