My friend suddenly ghosted me. Should I talk to her older sisters or her mom about it?

No, just forget about it. 

For one thing you are in the Talk show category,

Dump your friend is the best medicine ever, so why deal with it and let stress you out/

Talk to your friend in person.  You may very well find that you have jumped to erroneous conclusions. 

If you can't find a way to ask her why she's behaving like this, asking a mutual friend would be better.  Her family are very likely to take her side on whatever the issue is, regardless of the facts.