One thing I would consider with your mother's situation is that things COULD be even riskier with vaccines, when you think about how first, they aren't 100% effective, and that IMO- just from my conclusions based on my own research- a LOT of children are misdiagnosed simply because they are vaccinated. (meaning a doctor may blow off a "VPD"- hate that term, by the way- as something minor just by knowing the child has been vaccinated for that particular disease, when it's actually the real deal) So at least in my opinion, if they weren't vaccinated, it would be easier to pinpoint and confirm certain things for your mother's sake.
That said though, we've chosen not to vaccinate (if that wasn't already obvious ;) ). For us it's an ongoing thing, though- we feel it would be irresponsible of us to just make a decision and never re-evaluate it again. We stay as up to date as possible on research- on both sides- and pray about it regularly, and if for whatever reason we felt led to vaccinate for anything, we'd definitely consider it.
Initially we were going to vaccinate- with both of us in the medical field (and DH having grown up surrounded by it), we were actually VERY adamantly pro-vaccine. (which I feel gives me a pretty objective perspective anymore and I can relate so much to the people who oppose our decision, because I've been there too!) But something, I can't recall what (probably my MIL who is an RN turned pretty much naturopath LOL), made me hesitate with DD1, so we decided to do a delayed schedule. We waited until 4 months while we kept researching, then we put it off until 6, then until a year, and then we decided we were FAR more comfortable just not vaccinating. And that's they way it's stayed...even when I used to have some doubts, I knew that I was still more comfortable not getting them than getting them. If that were reversed, then the outcome may have been different from the start.
The longer we go, though, the more my eyes are opened to how powerful those little bodies really are...that God really did equip them with what they need. That doesn't mean we don't resort to medical assistance for some things, but just that I've learned to trust the natural process more rather than fear the possible outcomes. Also, I've seen my SIL's baby have seizures after vaccines and come to find out, SIL did too (and she had that horrible high pitched scream after her vax's, too)...so that reaffirms our decision as well, considering it's possible that could run in the family. But other things like the CDC Pink Book that states you're more likely to know someone who's had a reaction to a vaccine than someone who's had a VPD have also helped.
Thankfully we have a lot of support on DH''s side. His mother is AMAZING. And his FIL, while he's definitely on the allopathic side as a very experienced 45+ year MD, and he has seen a LOT of cases that contribute to him feeling like vaccine are still the best way to go, he is actually really helpful to us and sees how healthy our children really are in comparison to others (it's definitely been obvious, as my children DO get sick, there's no getting around that, but the severity is so much less, and they duration is always so much shorter!), and just from watching him over the last few years it would appear that he's starting to doubt them himself. ;) But he's always so encouraging when it comes to certain things...like pertussis, for example, he reminds us that it's endemic, he sees cases on a regular basis all throughout the year, that "outbreaks" aren't what we make them out to be, and even he will say that many of his dx'd patients are up to date on their vaccines. So it's just helpful to have his support in that regard. We also have an amazing doctor that I take the kids to, albiet only maybe once a year (just for the paper trail, as with FIL living across the road, even when we DO need something it's not really necessary for us to go see the other doc!). But she's an naturopathic MD and she has told us that if we ever need it, she will FIND a medical reason for a medical exemption for my children. She's very much on our side. She won't even administer vax's herself, but sends those pt's wanting them down to the public health clinic.
I will say though that my initial research into vaccines is what opened my eyes to almost all of the things I'm into anymore. I am a HUGE advocate of promoting gut health thanks to what I learned those years ago from vaccines.