Changing an object's respective gravitational field COULD have an effect on other objects, mild pulling forces and such but nothing really beyond that. I think that the effect would be more concentrated on WHAT it is that Molly is targeting, unless she were just projecting an altered gravitational field in the nearby area, in which case it just gets harder for people to move. 

I don't think she would be able to affect the gravity of the ground itself because 1. Ground is usually very expansive and much larger than she is able to affect, and 2. The effect that I'm thinking of is more like making the gravity AROUND someone or something more intense, so it would just make it heavier at best. If it were to affect things around the target by ways of pulling or vice versa, that would be a gravity well, which she can't do to living things and can barely do to inanimate objects, and not just an increase in gravity. Does that make sense?