That's the situation where the phone battery, with no different use by the owner, suddenly drains for no apparent reason. It turns out this is often caused by Google, and there's a simple way to halt the drain.
(April 2014) (Learn how and when to remove this template message) A network host is a computer or other device connected to a computer network. A network host may offer information resources, services, and applications to users or other nodes on the network.
That being said, Service Host(svchost.exe) is a generic service hosting container. Any number of required system services can be running in them, so I would not get rid of them. You can use Process Explorer to determine what services are running in the host container. My guess is it's Windows Update or BITS running.