The wife inherited a small amount of two rather obscure utility stocks when her mother passed away 4/26/11 which she sold in 2016 to raise cash. Looking for confirmation I properly estimated the cost basis for those. One was Pepco Holdings which I think closed at 18.83 on that day, and the other was RGC Resources which appears to have been 11.32 on that same day. Do those figures seem right, even considering RGC has split since then (I don't believe Pepco has)? Thanks for any help on this.

PEPCO is not a small obscure company. They provide power to DC and good part of MD.

Look up stepped up cost basis.

It depends - An estate can value assets at date of death or an alternative valuation date. If it the estate was under $5m you're probably safe in assuming that the valuation used was date of death.

There are online or printed books that provide stock values at any particular date. I assume that's the source of your numbers. (I didn't check.)

if she sold all of the stock she inherited then she can take the number of shares she originally received x the stock price on that date. You can ignore the impact of the splits. If you sold all the shares, all you need is total basis.

When you prepare your return you'll show acquisition date as date of death. You'll have long term capital gain or loss.

Hope this helps.