You can choose between some summoner spells but remember that ashe is very dependend to them.

FLASH is always a good choice esspecially for ashe because she doesn't have any jumps or speed ups.
You will need for clearing your buffs without loosing to much HP

Ghost ist also a good way to give your ganks some more power and it increases your chase potential

Ignite you may also use Ignite to counterjungle which i will explain later on.

Teleport is a good choice if u completly mastered ashe. You use ur ult while standing on base waiting for your homeguard to proc. Then you teleport to a ward or minion just out of sight by the target. if your ult hits the stun will be amazingly long and you can easily take a kill.