Will I have to do an amendment for forgetting to include form 1099-a? My husband had an HSA at a former job and I didn’t realize we would be getting this form when filed

What form did you forget to include? A 1099-SA? 

The 1099-SA reports on distributions from the HSA (i.e., you spent money out of the HSA for qualified medical expenses).

So if you didn't actually spend any money out of the HSA, then you would not have gotten a 1099-SA - which brings us back to my first question: what form are you talking about?

Please note that the HSA belongs to your husband and not his employer, so please do not close the HSA. If you close the HSA and take the money, then you will pay income tax on it as well as a 20% penalty.

Instead, you can continue to spend money out of the HSA until the account goes to zero - and then, you can close the HSA.