We need to cut down on our expenses, so that we are able to _________.

The sentence presents a scenario where there is need  to cut down expenses which implies a goal of financial stability or basic financial management. Of the options provided, Option A (Make ends meet) is an idiom meaning to have just enough money to pay for what you need, which fits the context of cutting down expenses. This is the ideal choice for the blank. 

The other options do not quite fit right. Option B (Tie up the loose ends) means to complete the final details of something (not related to finances). Option C (Be more philanthropic) means to give more to charity (opposite of cutting expenses). Option D (Be tax compliant) refers to paying taxes correctly, not managing overall expenses.

The correct answer is therefore Option A - make ends meet.