Expression

All of these are correct it just depends what you are trying to say.A. "to go back" means you are returning home after being somewhere else, thus, the meaning is slightly different from the other two sentences. I also think the verb "to go" sounds awkward when combined with the preposition "on" foot. If you said "to get back home on foot" that makes more sense. Or "to go back home by foot.""C

"It takes 20 minutes to walk back home." is also possible?

Yes, all are correct.

You can say,
I am back home.

but not appropriate to say,

I am walking back home. (back as an adverb in this example never makes sense)

I hold back my tears. (adverb, describe the action)

Hi lucas21c,
You asked me why I revised your examples the way I did in another post about being "recognized " and "acknowledged" and I said "every word we use in a context contributes to the intended meaning" If an inappropriate word is used, it can create semantic issues such as your examples below: The best choice is C because it is clean and short to the point.

My t