Pellet stove will take power to work right. A well placed and efficient wood stove would radiate heat without any power source needed.
Our wood stove in our lower level will heat our whole, smallish, house and the keep the heat from clicking on in below zero temps.
It has a fan but we rarely use it.
We could cook on top of it if we ever needed to also.

Plenty of folks up here have pellet stoves and they do heat great but need power to operate . Most have wood as an emergency backup, either a stove or fireplace . Really stoves are usually put in fireplaces up here due to their efficiency and heat radiating abilities.
The soapstone stoves heat up slowly but really retail their heat over time.
Pellets are readily available up here and pretty cheap due to the beetle killed trees they use for them, that is why many go that route for extra heat but not really as their emergency heat backup.
Pellets have the advantage for ease of use though, no firewood cutting or buying. Pallets of bags are way cheaper than a cord of wood and probably burn longer .

No one has mentioned the primary objection I have to pellet stoves....noise.

The auger and the fan put out a lot of noise.

I owned one for several years...replaced it with a propane stove. Quiet.

They are efficient. The auger and fan require electricity. Bags of pellets are 40lbs and cost about $6.50

depending on where her house is she may only use a pellet stove once or twice a yr. until the next bad storm comes in. firewood will rot if not used within a couple of yrs. I have a 1/4 cord of rotted outside now from sitting about 3 yrs.

Her system if I understand it right auto switches to AUX heat when the heat pump can't keep up. EM shuts off the heat pump and AUX heat and turns on heat strips for EM Heat. She has had this house less than a year and got a 1 year home warranty thru American Home Shield. First Tech came out and told her it was too cold for heat pump to keep up and just put it on EM HEAT and left and said it would take awhile for it to catch up.

It went from bad to worse. 3 days later they sent a different Tech. He said that unit has Auto AUX heat, and EM is only for if the heat pump completely quits. It heats well on HEAT since the temps got back up from extreme. That does not make sense to me. I always thought EM added heat strips to supplement the heat pump.

Reelslow, My system is very similar to what you said. The AUX HEAT is just that, it is designed to assist the heat pump. EM (EMERGENCY HEAT) Is when heat pump has quit completely and you are now on 100% heat strips. The different functions are time controlled, not sure of the times but example , heat pump runs 30 minutes & temp is not up to thermostat setting AUX HEAT KICKS IN. Another 30 minutes temp still not up to thermostat setting EM kicks in. Hope you can understand my explanation.

Wiseway makes a pellet stove, that does not require electricity.

This would be a good backup source of heat.