On death, all property "steps up" in cost basis, for tax purposes.
It may best be explained by example. Your mother bough a house years ago for $10,000. When she died it was worth $100,000. Your cost basis is $100,000. You later sell it for $110,000, paying $7000 in commissions and other expenses. You have a long term capital gain of $3000 (110,000 -7000 - 100,000 = 3000) to report on your tax return. If 3 siblings shared the sale proceeds, each would report a $1000 capital gain on their tax return. If the house was sold for a loss, a capital loss on personal property ("my brother was living in") is not deductible.
The $1500 proceeds you received is not relevant, nor is the "state taxes and other thing due"
