One dumpfile blames Probably caused by : MRVW24C.sys ( MRVW24C+272b0 ).
This is the driver from your networkadapter, your driver is from 2007 and is probably not compatible with windows 8.1.
Please update to windows 8.1 compatible driver, if this is not possible please remove this device. Driver Description: Linksys, NetGear, DLink or Marvell Wireless USB Network Adapter Driver Update Site: Official Linksys Support Site.
The other dumpfile blames your amd videocard Probably caused by : atikmdag.sys ( atikmdag+277ce ).
Please update to the latest version.