I recommend you look at powerline network adapters, with which I've had good success. You deploy powerline network adapters in pairs or larger groups. Once you sync the adapters you want to use together, you plug them directly into whatever AC power outlets are the most convenient. They use your house's AC power lines to connect between themselves, works great as long as there are no high frequency filters in the way. (So for example a good quality surge/noise suppressor power strip might block the powerline networking signal from getting through.) Each powerline network adapter has an Ethernet port; devices that are plugged into those Ethernet ports act like they are plugged into the same Ethernet hub.
So you might, for example, use three adapters:
(1) Adapter near the combo router in the basement near cable entry. Connect your combo router to the adapter. Now devices plugged into other adapters will act like they're plugged into your combo router.
(2) Adapter on the 1st floor, doesn't have to be near basement door. So you can position this where your extender can deliver the best signal to the 1st floor. Or you can install a new WAP.
(3) Adapter on the 2nd floor. You can either install a new WAP, or perhaps your husband can plug in his laptop or desktop directly into the adapter.
It's very hard for us to determine how many access points (or extenders) you need to get a good chance of getting strong coverage throughout your house. Construction materials matter a lot; and of course there's also just raw size. But with powerline adapters you gain a LOT of flexibility about where to put your wireless equipment. You might, for example, be able to put equipment on the actual stairs to give it a better chance of propagating signal both on the 1st floor and on the 2nd floor.