It's hard to say specifically without pictures, but if you're buying the house (and it sounds like the furniture in it) then it's ultimately your decision what you want to get rid of. It's always hard to get something from a relative because then you feel like you have to keep it. Ask them if they want it back, and if not tell them you are removing it. Don't feel guilty about it, it's your home.

Are you buying the seller's furnishings? The first thing you do is set a budget for the first year and then one for later. The first year typically has a lot of repairs when there's deferred maintenance. A young family puts a much larger load on plumbing, typically, than some older sellers did. A home warranty may be worth the money- check for well-reviewed companies in your area.

The cost of repairs and re model should also be considered when buying a sweet deal. Be sure to have a professional home inspection.

Wood furniture can be painted and look quite different. Metal can be spray painted to almost any finish. Glass doors can be removed. Dark shelving or TV's can be made to disappear by painting the wall behind them a dark color.

Post photos and we can give you more specific suggestions.

Unless they are transferring the furniture with the house then the decor is not important. Look at the bones and in fact if they are leaving the decor then still look at the bones, keep the decor you like and donate the rest.