Yes, first look for PROFESSIONAL mental health support. For your sisters, look for a social worker in your area or some other governmental support. There is most definitely help for people that have been set out of home. It's actually illegal to kick somebody out of the house without notice in most states, usually she requires 1, 3 or 6 months notice especially if she was paying some form of rent so you could go back with police to pick up her stuff.
As far as the religious aspect, nobody cares whether your mother is a pioneer or not, that has nothing to do with her health, in fact most congregations are desperate for such people and approve them in a heartbeat. The only questions at those meetings really are: did she do anything we know she was reproved for or could be disfellowshipped for in the last 6 months - no? - ok, scribble, approved then it goes through the rubberstamping process from there on.
Also, contacting elders will most likely do nothing. First of all you're disfellowshipped and therefore anything said against the organization or it's members is apostasy. The only way you can get through to your elders for anything, even criminal offenses like child abuse is if you have 2 active witnesses witness the same action (or with child sexual abuse, a repetitive pattern of it over the last 2 years). Some elders are nicer and will believe you if they already have a clue that there is something loose in the upper chambers. We had such a lady in our KH once though and the elders did nothing so she was pioneering until she started yelling at the top of her voice at the CO's wife *in the street in service* for having a fur piece (might have been fake) on the collar of her coat. She made the CO's wife cry and leave, after that she lost all privileges including answering at the meetings (not DF'ed though because her son convinced them she was mentally ill and that would be inappropriate - the son didn't get servant privileges for 10 years though after that)