I was lucky to be just watching this game instead of making the call... Bang bang, BR safe at 1st, clearly overrunning the base (in no way attempting to turn toward 2nd), and her base coach helps her come to a stop, by holding on after their "high 5". Defense wants an out.
Your call?

By rule, the runner is legally entittled to return to 1B so the coach is not assisting her, or interfering with the defense. So I can't call an out.

You may have an issue in that the coach's action would automatically turn the runner to the right, thus preventing her from making a mistake by atttempting to 2B, and thus being called out on appeal.

I have an issue with the coach being that far past 1B and near or on the foul line. I've chased coaches out of there before. If I am in "A", under certain situations I may move to foul area to make a call and I don't want to be tangling with, or have my view obstructed by a coach.

As I see it - no out, a few words with the coach to "get back where she belongs, and then congratulate the runner when she returns to 1B" - and play on.

WMB

If the runner was clearly turning into foul territory and clearly was not making an attempt to not advance then I would have nothing.

There was no advantage gained and I'm probably going against the rules.

Unless the coach is preventing the runner from advancing to 2nd.... but you said
I've got ridiculous request. If you want to get her out, Coach, get the ball there quicker.

Nothing. This is not an assist. Runner is safe.

I wouldn't call it, but I'd caution the coach not to touch the runners. Do you really think the defense is going to be talking about your supposed "bad call" for very long?

Last year I posed a question about a batter who hits one out of the park and then trips over 3B as he is rounding it. The coach helps him up. Even though he was entitled to home (plus, in this case, the ball was dead), the consensus was that he should be called out.

(I'm not sure I'd actually make that call, however!)

First time, nothing except a stern warning to the coach to stay in the box and keep his/her hands off the players. Happens again, in my judgment (I love that term), the coach was assisting the runner. Out! And maybe, just maybe a trip to the parking lot for the coach.