My friends mother passed away in May of 2015 and they took the month of May check out which she understood..2 years later they took money. Is this legal?

Were your friend and her late mother joint owners of the account in question? Commingling funds is a bad idea - Social Security, Medicaid, etc. will consider it to be mother's since she at least theoretically had access. Did she close this account and reopen an account under her name only? They are probably arguing that they wrongly paid money into this joint account in the past and now want it back from this account since theoretically your friend "inherited" the existing balance when mom died. Your friend should try to get bank statements and figure out if they are correct.

Your question is confusing. Would you please rewrite it? It doesn't make sense to me.