It doesn't seem that anybody try to show Lydia that she had committed something wrong, I don't see any advices or attempts to direct her not from her friends or her family. In the contrary ,they ,all of them, try to make what is good for her, which also I think it is good for their situations in life, but at least we didn't hear any reproof for what she has done with Wickham. And what vexed me more that they received her in Longboourn with smiles, and even her father he didn't dare to express his feelings of anger and disgust especially after what he has been through b/c of her doings. IMHO it is good that they try to find her and help them to get married and thank God for not listening to Mr. Collins:-

"Let me advise you then, my dear sir, to console yourself as much as possible, to throw off your unworthy child from your affection for ever, and leave her to reap the fruits of her own heinous offence. -- I am, dear Sir," etc., etc.

B/C anyhow she is young and needs to be directed , I could imagine Mr. Bennet took her the minute she enters the house to a private room and slaps her , just to wake her up and make her realize what she has done to herself and her family, may be you will say that is harsh but she is still young and this will help her manage her life in the future.
But instead of all of that ,the family listen to her insults to the sisters and especially to the elder one whithout any reply! :@