The consent of the husband is not a condition before performing the obligatory Hajj. However, his knowledge that she is going to perform the obligatory Hajj is a condition. Also, she must be in the company of safe and secure group of Muslims while going to Hajj. furthermore, even if the consent of the husband is not a condition in case of the obligatory Hajj, the wife should do her best to seek his consent and convince him by all possible means because the relationship between husband and wife should be based mutual love, affection and understanding.
As for the voluntary Hajj, husband’s consent is a condition. Almighty Allah knows best.