Malfeasance = wrong doing, misconduct, not doing what is expected of you (common for politicians) to hurt the other side
Nonfeasance = fail to act, refuse to do it in purpose
Misfeasance = doing the wrong thing in purpose
example :
catering company provide food and drink
if the company did not come = Nonfeasance
if they come and only provide the drink = Misfeasance
if the company poison the drink = Malfeasance