My dad was diagnosis with colon cancer, has all of the colon removed. what is the possibility that he will or will not have to have chemo/radiation?

Probably chemotherap: The fact that your father needed to have all the colon removed tells me that his cancer was multiple or he had many polyps in the non-affected area of the cancer. Chemotherapy is indicated by the type of cancer, the grade of spread to lymph node, liver or lung. Radiotherapy is indicated for rectal cancer. Age of the patient and health condition are relevant for the indication of chemotherapy.

Stage matters.: Chemotherapy is commonly employed if the tumor has spread to the lymph nodes, which are sampled at the time of surgery. Radiation is rarely used for colon cancer but sometimes is used when the tumor invades other structures or is incompletely removed.