Hatty a lady whom I know has been bothering others, how do I stop her?

a woman bout fifty six has been knocking on my back door a number of times over the last few weeks. She keeps asking for cigarettes and milk. I've given her some milk once, and advised her to seek help elsewhere. Since this i've had eggs and burned rolls left outside my door. Yesterday someone put a shrub container on my window sill. I think this woman is to blame, and last night i had 2 delivery companies try to say i ordered take away food. How do i stop this? She is handicapped i don't want to be rude to her.