I went to my best friends mams funeral even though I had moved away. Would be weird not too as her mam was good to me and was a 'friend' to me in her own right.
I found out in a memorial announcement on Facebook my old childhood best friend I hadn't seen in decades mam had passed away 3 years ago, around the same time as my own mam. Had I A) known that and B) been in a clear head space (was busy sorting my own mams death then) I would have gone because again her mam was always lovely to me.
It's less about the relationship with the 'friend' and more the relationship I had with their mam really.
Non of my friends that knew my mam came to her funeral, everyone had an excuse as to why they couldn't be bothered even though my mam was always really generous, supportive and nice to them.
Was kind of a kick in the teeth when I phoned my best friend to hear it was 'too far to travel'. My mam never moved and they never moved, its the same distance I traveled to her house every single day back in the day. I moved away but traveled over 10x the distance (and not easy to organize) to be there with her when her mam died but she couldn't be bothered to get the bus from right outside her door to the next town over and walk the not even 2 minutes from the bus stop to the cemetery.
I didn't expect the childhood best friend to show because like I said how would she know, I didn't find out until later about her mam either.
Its not about me at all, I have tonnes of friends that didn't know my mam and I expect nothing of that she was a stranger too them and I have DH for MY emotional support... it just shows how little those that knew her valued my mam in their life though. That they had just happily used her when it suited them though.
What was your relationship to the DECEASED person? Did they open their home to you, treat you like family, welcome you with open arms through your developing years, support you, help you? That's what its about now, not how many years you haven't seen the 'friend'. If you had a relationship with the parent then its about that.