Postpartum depression!!!

My sister just had her baby about 2 1/2 months ago and also has a toddler but is now going through postpartum depression... To the ladies that have had it. Is there anything I can do to help her?? I currently live a few hours away but if need be I will go stay a few days with her to help out with the babies but is there anything else that I can do to help?? It’s tearing my heart out seeing her like this!