Have to agree with others who have suggested that we should think about the age of those currently in nursing homes, and therefore what sort of music they might like. No-one left from WW1 now, and indeed have heard that WW1 songs can upset those who might have lost parents or other family members in that conflict. Even WW2 songs: very few of that era left now, so Vera Lynn stuff almost gone beyond: sorry about "We'll Meet Again" Heading rapidly for that category.
Probably 50s/early 60s stuff the order of the day: Lonnie Donegan, Chuck Berry, Elvis Preley, Buddy Holly, Everly Bros, Beatles, etc. But yes, a few wee light classical tunes shouldn't go amiss: anything for "Your Hundred Best Tunes"!