Yes, the meeting between Bill Clinton and Loretta Lynch was inappropriate. As the Attorney General and as an appointed official, Lynch was heading the investigation into Hillary Clinton's use of her email while she was Secretary of State. Bill Clinton's meeting with her in the middle of the investigation looks as if he was putting pressure on her regarding the ultimate outcome of the investigation.
As the Attorney General, Loretta Lynch is the "face" of jurisprudence in the United States. A private meeting with the husband of a person your office is investigating looks improper. At a minimum, it looks like her office may be biased and lenient on Ms. Clinton because of the personal relationship. At worse, it may appear that something underhanded occurred during the meeting to ensure that Ms. Clinton was not indicted. Ms. Lynch should not have met with former President Clinton.
While the DA claims it was merely a social call, the timing is far too inappropriate. It makes the rest of our nation wonder at the legitimacy of the investigation, the goodness of our retired President, and how far people are willing to go to pull strings to keep their friends and family in a position of power.
Yes, Bill Clinton's meeting with Loretta Lynch was probably inappropriate simply due to appearances. Regardless of what they actually discussed, their private meeting gave the appearance of impropriety. Both individuals are seasoned politicians who should have known about the consequences of such a meeting, not to mention the advisers who should have known better.