It's better than nothing, but no where near ideal.
Rifle and a scope for $300? First off, the scope is not much good in a home defense situation, and might actually get in your way. Red dot or simple iron sights are better for close range shooting. I'm guessing it's also a bolt action correct? Not a great choice for home defense.
For $300, you'd be better off going for a shotgun (there are plenty of pumps out there for under $200), or a cheap handgun (in price, not quality).
You can get a CZ-82 in 9x18mm Makarov for about $260.
9mm Makarov is a little more powerful than a .380. It's not something you would probably find on a Walmart shelf, but it is out there and is less likely to be effected by a buying craze than something like 9mm or 45 ACP.
Here's some hollow points for it.
This is only a suggestion. There are plenty of other good guns out there that would be within your price range.