First, I'll give the

speech and tell my story....
My 1st DD is an IVF baby. It took 3yrs and 4 cycles to have her. My H's counts were so far from normal, we were told the same thing - that it's not going to happen. So, I had Kate and declined birth control because we didn't need it.
I got pregnant again 12wks later. I got all the usual

speeches about how "that's how it always happens" and "now your body knows what to do". Blah, blah. Apparently, MY being pregnant created sperm in H and taught them how to swim.
I had my 2nd and mulled over my options. I didn't want more and pregnancy doesn't agree with me (this one nearly killed me). I went on the pill while I thought about different options. I knew it wasn't working right and I saw my OB, made the appt for the IUD and left with a different birth control pill to take in the meantime. A week later, I got another positive test and was pregnant (needless to say, my IUD appt turned into a pre-natal appt). I had no idea and I was pretty far along since the "period" I had on the pill wasn't a "period", so my Natural Family Planning method was pointless.
So, there's the

"don't give up, it can always happen" blah, blah speech. I always hated when people gave me that speech and hated it even more when people thought it would give me hope, but there it is anyway.
Did he have any testing to find out what might have happened in between him fathering kids and then not being able to? It could be something treatable - low hormones that can be dealt with (just never, ever let them give him anything like Androgel for low testosterone - synthetic testosterone is male birth control....there are other treatments for low testosterone), maybe an infection or a blockage that can be fixed surgically. You didn't say how he found out about his condition, but a good urologist that deals with reproductive issues could shed some light on things.
There is the IUI option...I'm not entirely sure what the church's stance on that is, but, if you're all clear and have no issues with blocked tubes, IUI could be an option.
I have several friends who have children through donated embryos. You go through an agency, pick an embryo, go through the IVF transfer and hope for the best. Again, not sure what the church's stance on that is - generally, they thaw more than would transfer because not all embryos survive the thaw, so that could be an issue if they thaw 4, all 4 live, but you shouldn't have all 4 transferred (my doctor's limit was 2 embryos). There would likely be an issue with discarding the 2 living thawed embryos. You could go with 2 and risk that none would survive and spend the time and money on medication for you just to not have anything to transfer.
You can do the same with IVF....just fertilize 2 of your eggs and hope for the best, but risk wasting the time and money. There's also the issue of, um, sample collection.... But, if the biggest issue is the embryo/life issue, you CAN get around that by only fertilizing 2 eggs and hoping at least 1 embyro develops to be transferred.
Good luck with whatever you guys decide.
I'm also sorry about your mom.
