As regards to the Ad-Hoc network:
on the android device try to manually define a new wifi network ("add wifi network") and use the same network name (ssid) you choose for your ad-hoc netwok on linux, and see if you can connect.
Then you have to check wich specific IP you have on the netbook and on the android device within the ad-hoc network (If the IPs are on the same sub-net its OK).
As regards to the Router solution:
(That solution will be more simple and straightforward to be able to share your MPD server)
If both devices are connected to the router then by default you can access from one device to another with the automatically-router-assigned IP (dhcp) the routher will gave to them. Do not try to fix the IP on the notebook, as you can be seeting an IP addres that is not within the routers IP sub-net (if you manually set, be careful).
Most probably, I believe, the ping does not work because the devices do not have IPs on the same subnetwork.
So I think the problem could be the manually-set IP.
For the Ad-hoc netwok check both IPs (laptop and device) and make sure they are on the the same IP netwowk (net-mask) for all this to work.
In a router solution (if you have one, use it!) do not set IP manually (the routher will handle) or, if set, use the same IP subnetwork of the routher for both manually-set IPs on the devices (be careful with IPs).