Please call/write/email them and say hello and something nice - particularly if they are elderly.
My darling Mum passed away on Saturday and so I've been contacting old friends and extended family. So many people have said how they had been meaning to get in touch with her and how much Mum meant to them and saying such lovely things about her.
Mum had dementia and so wasn't able to talk on the phone but I know how much a call would have meant to her.
I am just as guilty and I know how the time flies by but please don't leave it too late.