Hi @Byrnebaby, how are you doing? Hope you don’t mind my weighing in, as although @Spangleystar may well have wisdom to share from personal experience, I wanted to point you to a few places where others have talked through some of the same fears too.
There are some good threads in our forum’s Life after treatment section from people who’ve been through transplants and come out the other side, like the High-grade lymphoma: 6 months post-transplant thread, while not specifically Myeloma-focused.
We also have a personal story on our website from Elena, who has had two stem cell transplants. You can read it here. There’s also a separate story from Matt, who was immunocompromised post-transplant and writes about rebuilding to normal life (including eventually going back to the office and even to Glastonbury) which might feel a long way off right now, but is worth reading for what’s possible on the other side.
For the practical detail on infection risk and what households really need to do, Anthony Nolan have a really good patient-facing page on infections after transplant. It covers household contacts, the school question, and the balance between staying safe and not locking yourself away entirely. It also has a very reassuring ‘Longterm’ section 
For the really specific things like masking, your husband’s workplace situation, your son’s partner and the school, what your 100-day plan will look like - your transplant team will give you guidance tailored to your actual situation, and it’s worth raising all of this with them before you get there if the transplant is still being considered.
I hope some of our members who’ve been through similar situations at home will spot this thread too, and please keep posting whenever you need to.
Ceri