I’m not an accountant. Everything below is based on my knowledge, which absolutely should be second guessed and researched. The IRS.gov website has information. If you have an account with Fidelity or a similar firm they will know some things about inheriting accounts, and obviously an accountant is probably the best person to ask.
What estimated taxes does she have to pay? Her income would have stopped when she died I would assume. Property taxes are due when their due, which are most likely paid up, but you can check that online.
Estate tax exemption is at least $5 million unless it has increased already from the Trump changes. Is the estate worth more than $5 million?
If you inherited an IRA account and you are over a certain age you have to make sure you take anybreqyired disbursement’s. You not only owe tax, but can be hit with a penalty if you don’t. If she did not complete her required disbursement for the year, you need it to be disbursed, and you will be taxed in that as income.