In Malaysia, its famous with Datuk Kong, some tales have been said that Datuk Kong is a malay so cant offer a pork to him while in Hong Kong, there are no Datuk Kong this deities... From the religious view, Datuk Kong is not considered a God, Its considered a guardian spirits of one place or house hold... You can exactly see some constructions places, garden house, there sure have 1 Datuk Kong were worshipping by people cause people believe  Datuk Kong will look after the place where their staying...

In constructions places where the worker building house or building, most workers were very concern about worshiping Datuk Kong cause those workers would like to being safety during building any constructions in progress and never wish any accident have occur to them.

As based with what i knew about Datuk Kong thats Datuk Kong have separate into 5 of Datuk Kong.

Its been said that Datuk Kong who wearing into Yellow, Red & White was kind while Datuk Kong wearing in Black & Green were the most fierce one. The normal datuk Kong that we worshiping were the normal and kind one and sometimes around 5-6p.m, some may said Datuk Kong would appear into human form with a tongkat and would like to walking around his altar.. Some also may say datuk Kong would like to find people for conversation and if those people have fate to met up with Datuk Kong and having a conversation with him, that people will be in good luck coming afterwards....

Meanwhile the most fierce Black & Green clothing Datuk Kong were more into deep jungle or deep village and seldom have people will worshiping it.

It could be:

1. He had heart disease for a long time just that he doesnt know it. Heard of heart disease is a silent killer? He loves your grandmother very much too and could not cope with the loss. It is difficult and very painful when somebody close to us dies. The stress and grief that he had to deal with could have triggered the heart attacked.

2. Is your grandma buried? This one may sound hard to believe and since your grandma just passed away I'm not going to tell you out of respect. Go find out something regarding to Yin House Feng Shui. Yin house in feng shui means your grandma tomb.

There is a superstitious believe that when a funeral ceremony is held at home, all mirrors should be covered up with white paper. This is to prevent one from seeing the reflection of the coffin in the mirror. If anyone sees the reflection in the mirror, there will be a second funeral. This is very serious, dont play play.