Basically Neeko's behavior has undergone such a sudden 180 from being, for lack of better phrasing, selfish and useless to now being productive and grateful, that Mom is confused as to how she should be reacting. So she's taking her confusion out on Neeko, even though she knows deep down that she's just being stupid. The "happy or angry" face is exactly that, she so caught off-guard she doesn't know IF she should feel happy or suspicious because it's totally now how she's used to dealing with her older daughter.
That's how I read it at least.
EDITED: Just realized translations changed, changing some of the mood of the comics. Whoops.
If your friends are coming, then why don't you clean the entrance and the corridor too?Oh... I was planning to.The trash.H-Here!I'm an idiot too, aren't I...Thank you, for everything...Mom! Can I eat this cake!? Leave some for Neeko.
VerandaNeekoImokoMama2F Rough layout