In preparation for funeral rites for a late father, between the mother and first son, who is to make decisions?

This is in the Nigerian context, kindly share your knowledge on this subject. Thank you

In my own side, when a man dies, his first child carries the responsibility of the burial. If the first child is a female, her husband buys the coffin. I think it is believed that the grieve will be too much for the wife that's why the I children have to take responsibility for their father's burial .

selfwife:
In my own side, when a man dies, his first child carries the responsibility of the burial. If the first child is a female, her husband buys the coffin. I think it is believed that the grieve will be too much for the wife that's why the I children have to take responsibility for their father's burial .

What if the mother is able to pull herself together and has a preference over how the disposition of the remains should go? This is usually the case where there are wide difference in tribal and religious inclinations of either parties. What do you think?

In my opinion, I think the Next Of Kin Hierarchy is key. I stand to be corrected...

In order to qualify as next of kin in this situation, a person must be over 18-years-old. The relationships listed below usually apply to biological, adoptive, half-, and step-relations equally.

Spouse/domestic partner

Children 

Parents

Siblings

Authorized guardian

Grandchildren

Great-grandchildren

Nieces and nephews

Grand-nieces and grand-nephews

Grandparents

Aunts and uncles

First cousins

Great-grandchildren of Grandparents

Second cousins

Fiduciary (a legally appointed trustee) 

In some states, a close friend who is familiar with the deceased’s wishes may qualify as next of kin if no one on the above list is available or able.

It all depends on the culture... In mine, it is the 1st son if he has come of age

Then she can continue. She can even sit by the graveside. Most people won't care again and her children will call her stubborn.