When my grandma passed away, I did all the thank you cards for my grandpa. He wanted everyone who attended the funeral,and/or sent cards,floral arrangements, and/or offered any assistance at that difficult time to be acknowledged.
Since that was he wanted, that was what I did. My Grandpa was about 87 at the time, and it would have taken him years to get them all done. We made a day of it, as I worked, he reminisced about my grandma. It really is a fond memory, as my grandparents were really cool!
And, taking this off topic, I also was the "pen" behind their Christmas cards for several years. It always cracked me up, that my grandparents would specificall tell me to make sure that "they" sent a card to my family. So, every year, I would address a card to me and my family on their behalf. And, still, as busy as the holiday season would get, I would forget about those cards as soon as I mailed them. I was always surprised a couple of days later, when I opened the mail. Again, just like the funeral cards, doing their Christmas cards is a fond memory of my grandparents.