OnlyThe onely thing I could do was to give them as much scholastic knowledge as much as I could whenI could each time they came to athe small classroom that was in a hospital where they went to see their doctorsin their hospital.

This sentence is a little long. I tried to make it easier to read.
"Only one thing I could do" should be "The only thing I could do"

Some students came to the classroom everyday, and other students came only once a week or less.

So normally, we write "every day" with a space when we use it like 毎日: "Every day, I go to the store." or "Every day they came to the classroom."
We spell it without the space when we use it as an adjective. I think this is like 日常. "The man who saved the child was just an everyday hero." "The king does not care about everyday problems." "We should not fight over everyday conflicts."
In business, there is a strategy called Everyday Low Prices (EDLP), which means you do not have sales/discounts and charge the same price everyday. So, you can't beat your competitors sales, but, customers can be confident that if they buy from you today, they won't miss out on a sale tomorrow because your prices never change. That is spelled without a space.

There is nothing wrong with saying "come to the classroom," but it is a little more natural to just say "come to class."
Adding "only" is a little better because it emphasizes the contrast.

Now, I wonder how much they were struggling for themselves.

Now I know they never wasted their time at all, and they really needed enough time to do every little thingto take their time to learn.

We can stop or run away from darkness anytime, anywhere.

Today, I suddenly rememberthought of my old students todayagain.

You can also say "former students."

I hope they are walking their own paths with a smile.

My Memory Aboutof My Students

Only one thingAll I could do was to give them scholastas much academic knowledge as much as I could when they came to a small classroom that was in athe hospital where they went to see their doctors.

Some students came to the classroom every day, and other students came once a week or less.

Now I wonder how much they were struggling for themselvesinternally.

Now I know they never wasted their time at all, and they really needed enoughthat time to do every little thing they did.

We can stop or run away from darkness anytime, anywhere.

I suddenly remembered my old students today.

One of my students will start work at an animal hospital veterinary clinic this spring.

I hope theyall my students are walking their own paths with smiles on their faces.

OnlyThe onely thing I could do was to give them as much scholastic knowledge as much as I couldpossible when they came to athe small classroom that was in athe hospital where they went to see their doctors.

"...was teach them as much as I could"
An alternative that sounds more fluent and more or less carries the same weight and meaning since you were a teacher.

Some students came to the classroom everyday, and other student while others came once a week or less.

Now, I wonder how much they were struggling for themselves.

Now I know they never wasted their time at all, and; they reafully needed enoughthe time to do every little thing.

I suddenly remembered my old students today.

One of my students will be working at an animal hospital this spring.

Or "...come spring"
"...in the spring".
"This spring" is just fine though!

I hope they are walking their own paths with a smile.