Python analysis script for Nonprofit

You are an expert in this kind of work, and you know the Nonprofit sector from the inside.

## Your task
Write a Python script using pandas and matplotlib that loads [FILE NAME], cleans it, computes donor retention and cost per beneficiary by [DIMENSION] and month, and saves two charts. Our columns: [COLUMNS]. Comment the code for a team member at a nonprofit organisation funded by donors and grants who is new to Python.

## About my situation
- Who this is for: donors, volunteers and beneficiaries
- What we must respect: limited budgets, grant terms and transparency to donors

## What matters in Nonprofit
- Numbers that matter: donor retention; cost per beneficiary; funds raised; programme outcomes; volunteer hours; fundraising ROI.
- Tools commonly used: Google Workspace; a donor CRM; Canva; crowdfunding platforms.
- Rules and standards that usually apply: charity registration and reporting (12A/80G and FCRA in India, 501(c)(3) in the US); grant terms and restricted funds; donor privacy; safeguarding of children and vulnerable people; transparent use of funds.
- Rules differ by country. If I have not said where I work, ask me, and do not present one country's law as if it applied everywhere.

## How to work through it
1. Load and clean the file.
2. Compute the metric by dimension and month.
3. Save two charts.
4. Comment every step for a beginner.

## What to deliver
- Complete Python script
- How to run it

## Rules
- Make every point specific to my situation and my industry; replace generic advice with detail that fits.
- Use plain language, short sentences, and tables where they make the answer easier to scan.
- Use only the facts I give you. Do not invent figures, laws, sources or quotes. Mark anything you had to assume with "Assumption:".
- If something important is missing, ask me up to 3 short questions before you start.

## Before you answer
Check your draft against this list and fix anything that fails:
- Every number comes from my data or is marked as an assumption, and correlation is never presented as cause.
- It is written for a nonprofit organisation funded by donors and grants; nothing in it would read the same for any other business.
- Nothing in it breaks limited budgets, grant terms and transparency to donors.
- Every item under "What to deliver" is included.