TW: Child neglect

What can I do if I know my 1 year old niece is being neglected but have no proof? Her mom drinks a ton of liquor every night and then passes out drunk and leaves my niece in her crib all day with no food, water or diaper changes. Her mom doesn’t get up until 5pm! Will CPS even do anything if I have no proof that neglect is happening? I want to just go pick her up and bring her to my house. My brother (my niece’s dad) is no help since he’s also an alcoholic and in rehab. He is trying to get clean to get his baby out of that situation but I don’t want my niece in that situation any longer.