Put diesel to a petro car

My sister put disel to a normal gas car - honda 2006, less than 8000 miles (long story).

According to her: ---
She put 4-5 gallon, and there more gas in the tank.

She drove almost 100 miles, and then found that the car goes roughly.

She stopped, and had a good dinner, and found that she couldn't start the engine.

Ten minutes later, she put normal gas to the car, and she could start the enginne.

It was rough, however it got better, and now the car goes just fine.

---

Before she tells me the story, I didn't recognize any difference, but I am just alarmed that she drove it almost 200 miles after she put disel.

What am I supposed to do?
Can there be some damages to the car?