You may not be a programmer but this task requires someone who have some background on the matter, AND we are talking 30 years old stuff?
If you need to run .XLS, then you need to buy Microsoft Excel to run it. With Qbasic, and there may had been a couple of versions of it if my memory serves me right, was sold by Microsoft and maybe another company. These stuff is so old it maybe passed on to the public domain, I don't know, up to you to research, that's why my reference go GOOGLE, and you found nothing?
What I can offer you is, here is another problem, I happen to have a few old .bas that I am no longer able to run after things went to 64 bit. Qbasic was when things were 16/32 bits, so even if you find the App, you may have to run it on an old 32 bit PC.
You are probably looking for a qbasic compiler, maybe a run time interpreter, if they still exist.
If this stuff is beyond you, may want to hire someone more qualified to dig into things. In free forums like this, all we can do is to direct you where you can obtain more information. There are no consultants here.