I'm going to give you a slightly different opinion

and I can be frank. It is not intended to be critical but only from my experience as I have been through many down sizes, up sizes and reorgs over the years. It is part of business today.
You employer may hear your input but they are under no obligation to take your advise. It is very unlikely you "caused" her layoff. Owners make those decision on a whole range of stuff including bottom line, client interfaces and their own experience. It may be that her assets are simply not needed in the new business. It isn't personal. There is no way you are ever going to know fully how they came to that decision.
If your coworker is as capable as you believe she will be fine. She may even end up in a better place then you

I know unemployment is bad but people still have to leave jobs and people still have to fill those positions.
There is no way your employer will let you "give" her a job. It isn't really appropriate to ask because it shows a lack of confidence in their decision. Trust in a new, small business is critical. Unless you are very close to her she may even not that be upset about it.
Finally, give yourself more credit! They obviously think highly of you and respect your work. There is everything right about feeling good about it. I get that you feel guilt but it really is unfounded given all the factors involved.
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