Assuming you lived in House B for 2 out of the five years leading up to the date of sale, you can treat this home as your principal residence for purposes of excluding the gain on the sale. If you are filing a Married Filing Joint return, you can exclude up to $500,000 in gain. You wouldn't be able to exclude the gain on the sale of another home for two years.
See this TurboTax help article for steps on entering the sale of your main home in TurboTax.
