It's not clear exactly what you mean by "more than 50miles away." The requirement for a partial exclusion of gain is that the distance from your current home to your husband's new job location is at least 50 miles more than the distance from your current home to his old job location.
If you meet that requirement, and you and your husband both owned and lived in your current home for exactly one year, your maximum exclusion would be $250,000. If your gain is only $150,000 the entire gain would be excluded, so you would not pay any tax on the gain.
However, if you sold another home less than two years before selling your current home, and claimed an exclusion for that sale, you cannot claim any exclusion now. In that case, the full gain would be taxable.
You should take a look at IRS Publication 523, Selling Your Home, particularly the section "Does Your Home Qualify for a Partial Exclusion of Gain?," and use Worksheet 1 in that section to calculate what your exclusion would be.
