How to stop cat from attacking me?

I'm cat sitting for a neighbor they r gone for 4 days and this morning I whent to feed the cat she wouldn't let me near her I barley was able to change her food without her clawing me she wouldn't let me touch her water or go to where I need to to change the litter box... At the end of the visit her pupils were dilated ... I don't need her to like me I just need her out of my way... I have to go back later HELP