Is sale of deceased mother's home, taxable income?

Inheritance is not taxed.

(the estate might have been taxed, but that would be before you inherited)

Any GAIN in value between the value of the house when your mother died, and the price you sell it for, is taxable. Unless you moved in and made it your primary residence for 2+ years.

You cannot "slip" property of any kind into a Roth IRA. Even if you could, it would be subject to the $5500 annual limit.

You can purchase real estate within an IRA with the money that is already there.

You CAN'T put the proceeds in ANY form of tax advantaged account, unless you could put that amount in the account from regular income.

Only if you sold it for more than it was worth when you inherited it.

Only if the sale price minus sales expenses is greater than the value of the home on the mother's date of death.

Roth? No.

That's part of settling the estate. In probate, all your mother's debts & final expenses must be paid in full, e.g. pay off balance of any mortgage, pay her final income tax bills, probate court & legal expenses, etc. What's left, if anything, is divided among the heirs according to her will. They don't pay taxes on what they inherit. Any estate tax would be paid while in probate.

only any increase in value since she died

Knowing Uncle Sam, possibly and probably.