Lady Catherine seems to one of those wealthy people who assume that needy people simply don't know how to make ends meet. The narrator doesn't say that Lady C offered any monetary help, or even any food or clothing, just a good scolding so that they can somehow learn to have more. That's not very helpful and not very charitable, either.

Likewise, her concerns with the locals having quarrels seems to me to be more noseyness than concern for justice and/or mediation. She scolds them into harmony -- probably telling them something like they have no right to be quarrelling with one another when they are so fortunate as to live in the neighbourhood of Rosings. Mr Collins would certainly agree with this, I am sure. :-)