furnace shutting off

I would start by checking the filter

Sorry to hear about your husband. The low bang is probably the ductwork contracting after it cools down or deflating and making a bang. Nothing to worry about. I assume it is an oil furnace. You should NEVER press the reset button more than once as it may pump unburned oil into the chamber and that is dangerous. There is a reason the burner won't fire and all I can suggest is try a different repairman and maybe he will spot the problem. Perhaps one of your neighbors or friends can recommend someone they have good results with.There are about a dozen different reasons it may fail and some are fairly simple if the serviceman is experienced.

Good Luck

As above, sounds like the duct banging.

Have you checnged or cleaned the air filter lately.
A dirty air filter can cause the temp rise to be high enough to cause the duct work to bang.

The Thermopride, has a life time limited warranty on its heat exchanger.

Your service man just missed what is causing the problem. No need to replace furnace.

thanks everyone, I will follow up on your advice. When the problem is fixed I will let you know what is was.