Wow what a huge thing to commemorate, that is a great idea!
I've used this site a few times to get facts from different years when doing heritage pages:
You could use the facts from each decade as a theme for the album, do 2 page spread for each decade and find a fun way to incorporate the facts into your pages. Use tags to jot down a few facts from each time period.
Be sure to check out the gallery here, you can do a search for any specific key words you are interested in or just poke through to get inspiration. But whatever you do I'm sure you're grandmother will be so touched by your thoughtfulness!