What is the significance of grandma's funeral grapes of wrath?

According to "Grapes of Wrath", the death of Grandma is miserable to the family. The family had a discussion of how burial of Grandma can be done. At that time, they analyzed that, people are spending lots of money for funerals which is not at all required. That expensive money which is spent during funeral procedures can be used for future.

So the family decided not to spend lavish money but anyway they should bury Grandma in an respective way. This was the significant aspect in Grandma's death.