General sense of helpfulness:
* Helpfulness - This is the most common and straightforward option.
* Assistance - This emphasizes the act of providing help.
* Support - This emphasizes the act of providing aid or encouragement.
Specific instances of helpfulness:
* Help - This refers to the act of assisting someone.
* Aid - This refers to assistance provided in a specific situation.
* Favor - This refers to a kind act done for someone.
The best noun to use depends on the specific meaning you want to convey.