Yes, it was improper for Loretta Lynch and Bill Clinton to meet privately. As the attorney general, Loretta Lynch is the head of the Justice Department, which is currently involved in the ongoing investigation into Hillary Clinton and her tenure as the secretary of state. Ms. Lynch should not have met privately with the husband of the subject of her office's investigation.
The meeting of Lynch and Bill Clinton seems awkward in light of Hillary Clinton's email scandal probe. Not that any meeting with high profile politicians is ever very private. Judicial Watch claims the Bill Clinton and Loretta Lynch meeting is unethical and violates the public's trust in the Justice Department. With Bill Clinton's wife running for President, perhaps Bill Clinton should step away from politics, at least distance himself from trying to make heavy political decisions, and let a committee take over. The timing of the meeting is terrible. This meeting acts as leverage for Trump, and creates undue controversy for Hillary Clinton. Bill Clinton could wait until the election is over, and re-evaluate his place in politics then.
High-profile people meet with each other all the time, and most of us don't even know anything about it. The fact that these two met means nothing, given that we don't know the true reason for their visit. Nothing can be accomplished by two people anyways, and if there was any proof of misconduct, this meeting couldn't hide that.
I do not know the details os Loretta Lynch meeting with President Bill Clinton. As a result, I am unable to say that she acted improperly by meeting with him. As such, I must give her the benefit of the doubt by assuming that her actions were appropriate and within reason.