You are a guest worker. As such you can sponsor dependent spouse and children only. A parent - even one requiring your care - does not qualify.
A person without health insurance will find it difficult to obtain care. Even USCs with insurance have difficulty finding doctors taking new patients.
If your parent is so wealthy as to be able to fund medical care in the US without insurance, his child would have no need to work. It is not unusual to have medical bills exceeding $100,000. Even simple day surgeries can exceed $25,000.
Why should the fact that your husband has never been to your home country affect the fact your father cannot legally reside in the US? It is your and his choice that you both have not visited.
Since you have chosen to work in the US, you also need to abide by US laws which do not permit your nonresident alien father to live in the US just because he needs care.