Answer:
Some are genuinely giving back to the community:
Some MNCs are engaged in Corporate Social Responsibility (CSR) and Sustainable business practices because they genuinely care about the communities they have a presence in and the earth as well. With this is mind, they find out ways to give back to the community to ensure that people's lives are touched and improved so that the wider community benefits from the success of the MNC.
Brand Strengthening and Recognition.
Sometimes MNCs get involved in CSR to build their brand because people would associate their brand with the good works they do. This would go a long way in improving their sales figures as well because people want to support a company that supports its communities.
Tax Considerations.
Various tax credits exist for MNCs across many countries and tax regimes to reward them for their CSR activities. MNCs therefore see this as a chance to kill two birds with one stone as they get to use money that would have gone to taxes to improve their PR standing.