Yes, your husband can enroll in Medicare Part B at any time after he turns 65. But because he has waited more than three months after the end of his birthday month, he will have to pay a Medicare Part B penalty. But he'd better hurry and enroll by March 31, or else he'll have to wait until next January 1 to sign up, and the Medicare Part B penalty will be higher.
Here's how it works. When your husband first became eligible for Medicare Part B, he could have signed up for Medicare Part B, without penalty, anytime within three months after the end of the month he turned 65. In his case, within three months of the end of November 2008, which means by February 28, 2009. Because he didn't sign up for Medicare Part B by the end of this initial enrollment period, he has to wait until the Medicare Part B general enrollment period. The general enrollment period runs from January 1 through March 31 each year. So, he has only until March 31 of this year to sign up for Medicare Part B, or he'll have to wait until the next general enrollment period, which would begin January 1, 2010.
If your husband signs up for Medicare Part B in the general enrollment period this year, his coverage won't begin until July 1. Also, there is a monetary Medicare Part B penalty for delayed enrollment: His monthly premium for Medicare Part B coverage will be 10 percent per year higher because of his delay in enrolling.