Number 1. It means we will contribute to the best of our abilities. The second sentence is not a complete thought and while someone might say it poetically, it is not normal English and its meaning is very much subject to interpretation.

We will do what we can to help It takes the infinitive form It could also be stated as: We will help in whatever way we can.

for me is important understand if after the modal verb I can put a verb with the infinitive form. I known that is a mistake write: "... can to help". Instead, is correct write: "... can help". But the oxford advanced learner's dictionary have the follow example: "We will do what we can to help" I am very confused. Thank you in advanced for your time. Maurizio