"For cause" is often stated, "for good cause" or "for just cause." Generally it refers to a reason that most people would agree justifies an employer's termination of an employee, like
* not showing up for work regularly, i.e., "attendance issues"
* conviction of a serious crime
* showing up to work drunk or under the influence of drugs
* violation of policy against sexual harassment
* theft of company property
Employers pay people to show up and do work. If they don't show up regularly, it seems apparent that the employer can and should fire them.
These are just general principles of what's widely considered to be good cause, based on the facts you provide. I don't know what the law of North Carolina is specifically, as I don't practice there, so don't take this as legal advice. If you need legal advice, please consult a lawyer who holds North Carolina licensure.