1. The key for nice performance is a good ssd.
240gb Samsung evo is best for reliability and performance.
Unless dad is storing videos or large files, that is all that is needed.
No need for a hard drive at all.
2. The aforementioned G4560 is a very good choice. The included HD610 graphics is quite good.
3. With a 7th gen cpu, buy a B250 based motherboard. H110 is cheaper, but not all will have the enabling bios update to be able to run 7th gen G4560 processors.
4. Buy a 2 x 4gb DDR4 ram kit. Dual channel ram is faster, particularly for integrated graphics. 2400 speed is fine.
5. All motherboards will have an Ethernet port. If you need wifi, look for a motherboard with included wifi.
I like smaller cases, the Silverstone sugo mentioned above is fine.
You will need a ITX motherboard for that.
6. Do not go cheap on the psu. look for a tier 1 or 2 unit on a list such as this:
http://www.tomshardware.com/forum/id-2547993/psu-tier-list.html
300w is more than enough.
Seasonic is always good.
I mihttps://www.newegg.com/Product/Product.aspx?Item=N82E16817151074ght pick this tier 2 Seasonic s12II 430w unit for $25 after rebate: