Use of "although" and "yet" in a sentence together
I many time speak although and yet together in a sentence like

Although it is very expensive to afford, yet she can afford it.

Although she has lot of assignments, yet she can do it.

Although it is a night time, yet she can go outside.

Are these sentences correct , if not how to correct these kind of questions starting with "although". Expert opinion from expert English grammar teacher highly will be highly appreciated

Question

Use of  "although" and "yet" in a sentence together
I many time speak although and yet together in a sentence like

Although it is very expensive to afford, yet she can afford it.

Although she has lot of assignments, yet she can do it.

Although it is a night time, yet she can go outside.

Are these sentences correct , if not how to correct these kind of questions starting with "although". Expert opinion from expert English grammar teacher highly will be highly appreciated

Answer

I would not use yet and although as you have typically.

"Although it is very expensive to afford, yet she can afford it" is better written, "Although it is very expensive, she can afford it."  Yet is not needed, because "although" already lets the reader know that there is a caveat to her being able to afford "it". 
You can also say, "It is very expensive to afford; yet, she can afford it." in which case you can leave off although.
"She has a lot of assignments; yet, she can do them."
"Although it is nighttime, she can go outside."