So sorry for your loss, and it’s understandable you are feeling sensitive that things you “expected” to happen didn’t. The fact that 6 work colleagues turned up shows people do care, perhaps they even decided it best not everyone turn up and maybe just some of them to represent the work colleagues. It may also be that some had commitments and they could not attend, and maybe they feel bad which is why they haven’t spoken to you about your mum, also sometimes people avoid bringing up the conversation about someone who has passed in case it makes you upset. Whatever it was, if YOU believe that these people were good friends before your mums funeral, then this should still be the case. I’m sure as time goes on they will find ways of supporting you, just don’t hold it against them… people have different ways of dealing with these things. As others have said, many of the old traditions are fading away, sadly.