My mother came to visit me.

This morning, my mother departed for my apartment in order to get repair her laptop.

It was so suddenly event.

The distance between my mother's home and my apartment is around 300 km, so traveling time become around four hours by car.

In that four hours, I had to clean my room desperately because ... as you may have guessed.

After four hours, my mother reached my apartment and I invited her to my room.

She seemed to be satisfied and praised me, haha, yes.

I repaired her laptop quickly, then we went to a hot spring.

We healed our body fatigue, and ate dinner while talking various things.

It was so nice time.

• This morning, my mother departed for my apartment in order to get repair her laptop.
• This morning, my mother departed for my apartment in order to get repairs for her laptop.

• It was so suddenly event.
• It was so unexpected.

• It was so nice time.
• It was such a nice time.

• This morning, my mother departed for my apartment in order to get repair her laptop.
• This morning, my mother departed for my apartment in order to get repairs for her laptop.

  It is accurate to say "departed" but it sounds a little funny in this sentence. I would just say "...my mother left for my apartment," or "...my mother came to my apartment."

• The distance between my mother's home and my apartment is around 300 km, so traveling time become around four hours by car.
• The distance between my mother's home and my apartment is around 300 km, so the traveling time become is around four hours by car.

• We healed our body fatigue, and ate dinner while talking various things.
• We healed our body fatigue, and ate dinner while talking about various things.

  "We rested," or "the hot spring was very relaxing" might be more natural than "we healed our body fatigue." You can say that if you want, it is okay, but it sounds a little bit artificial.

• It was so nice time.
• It was so nice a time.

  "It was such a nice time," would probably be the most common.