Hi Seansean, I'm sorry for your loss. The death of a parent is a traumatic experience.
Unfortunately, in my experience, some people just don't know how to deal with death. They don't know what to say or how to react. There are countless reasons for this and if I were you, I wouldn't dwell on it, you have enough on your plate at the moment.
I would take comfort from the fact that 6 people did take the trouble to attend the funeral and support you. I hope that you had other family and friends there too. Those people will be the ones who have more understanding of your situation and can be there for you in the long term. Best wishes to you.