Has she actually asked for anything for the wedding?

Regardless, it sounds like you and your husband need to be on the same page about what/how much you feel would be appropriate, given the considerations you've laid out. This sounds like a delicate situation, but hopefully you can have a frank conversation about it. (Red flag goes up whenever I see "whatever you decide")

Also since it sounds like she hasn't gotten very far in the way of planning, it might be a bit early for her to say how she would like you to participate. There are many ways to carve a wedding up, financially speaking, as well as in terms of all of the sentiment and emotion that people attach to those pieces. Perhaps just letting her know that as she gets into planning that you would be interested in helping in some non-specific way would be one way to open up that conversation.

Just as an example, DH and I paid for the lion's share of our own wedding, but his parents paid for rehearsal dinner and my parents picked up the tab for morning-after brunch. My mom wanted to do more so I put her in charge of gifts for guests. Other things that could be carved up: flowers, music, photography ... the list goes on.

But I would let her take the lead, and then be prepared to respond with something that you and your husband can see eye to eye on.