(a) you give away your money - gift tax
The person who receives the gift doesn't owe any tax.
If you give it out in small amounts, there will be no gift tax. It could have tax and Estate issues for you depending on the size of the gift, the timing, and how much you give away in total.
Of course if you give it away to a charity you could deduct the gift.
(b) you loan someone some money - tax free??
It there is a loan, and and you collect interest; you will have to declare that interest as income. The IRS will expect that you charge a reasonable rate, otherwise the interest could be considered a gift. Not sure what a reasonable rate is with savings account earning 0.1% per year.
(c) you pay back the debt you owe - tax free ?? tax deductible ??
The borrower can't deduct the interest they pay, unless it is a mortgage on the main home, or a business loan. I will admit that there may be a few other narrow categories of loans that would make it deductible for the borrower.
If the loan/gift is for the down payment on a house, the lender for the rest of the mortgage will want to make sure that the gift/loan nature is correctly documented. The need to fully understand the obligations of the homeowner.
If it is a loan between family members the IRS may want to see the paperwork surrounding a loan, to make sure it isn't really a gift. They don't look kindly on loans that are never paid back and no interest collected.