Home only - shotgun is a good start, mossberg or remington pump. I know on mossbergs you can switch out barrells. 18 inch for home is bueno. 

Thought of having something with you outside of home - 9mm handgun, go to a range, rent several and pick the one you like best.  There are several in the $500 range that are all good. For concealed carry there are several. Stick with 9mm.  Side note, I love .45 but not ideal carry so if I carry it's 9mm. 

Next step:

AR-15  if you don't like the look go with Ruger Mini14

AR-10 seriously consider this before a AR-15. It's meaner than an AR-15

.22 for survival/plinking, everyone should have one. 

You can seriously think of a specific weapon for every situation. Then you think you need a bunch. Reality, a shotgun, handgun, and rifle will pretty much cover anything you run into. 

Good luck,