A lot of things came to me as I read this.
The strongest initially is that this is a man who simply has a hard time expressing himself. He doesn't just come out and say what's bothering him but seems to have a sensitive nature just as well that the daughter is probably familiar with.
She, on the other hand seems to run by passion and too may be sensitive but just blurts.
You're right. There's frustration where he doesn't know how to fix what's going on with the daughter. At the same time, there are things that irritate him that in his own life he may normally, be able to just accept with the increasing guilt of not being able to "fix" everything, have some steam rising to the surface.
It may not be you so much but just the target closest in proximity to the situation. He may not really
want or enjoy how he's dealing with things but displacement through the pets or little things, may be an attempt to keep his sanity or on a level vent and deal with eveything that's going on.
Having kids has about a 1 yr. grace period. Between the first nine months, even months prior to if you're trying to
get pregnant, you're not actually dealing with the physical temperment of another Human Being, crying, needing, demanding, and eventually running around, expressing themselves. Plus for a time, you may have the luxury of also having the empathy from others of being a new mother, who are willing to pitch in. So, there's a lot of extra time to dreams, hopes of what you want or think it'll be like.
Then ---> REALITY SETS IN.
I think the dad feels guilty, not giving money to her and the more she goes without, she's expressing
to the world how bad it is.
There are other ways you can help though, be there, other than just money. Sure that helps but it isn't always realistic because the needs of children are neverending.
You could get together names and numbers of organizations, resources (like a rolodex) so when she just doesn't have the energy or know where to start looking, she can open up a notebook and there they are

It's something that even the father may feel better being a part of to be able to contribute to.
Handing money over money can tend to go more to emotional gratification moreso that where it's supposed to go. Then you end up being short no matter how much you give them and with good justifications (to them) where it all went. So there isn't really isn't a point where you just go "Whew!"
With resources and a little extra financial help, they are things you can in good heart continue to offer with extra time you might have, a new mother may not, while having some breathing room to yourselves.
It may be a grandchild but it's her child, the mother needs to step up and care for. That often means going without, yourself, as the parent.