What would you do?

there is an elderly woman (in her 70's / 80's) in a large supermarket chain and when she gets to the medicine aisle you see her open her handbag take an item of the shelf and hide it under her purse and then walk away.

So what would you do...

a. tell a member of staff

b. approach her and say what you have just seen

c. ignore it - she's old and might not have much money

would your answer be the same if she had stolen an item of food rather than medicine?