What is a good financial investment to gift my mother?

I want to make a financial investment for my mother—something that won’t strain my finances but still provides her with a sense of security. We are financially stable as a family, and everyone is independent, but since I’m the youngest and just starting my career, my income is currently the lowest. While this isn’t a problem right now, I still want to set up an investment for her that assures her that her needs will always be taken care of, especially because I’m considering leaving my job for various reasons, so the possibility of not earning for a while is real.

I don't want to buy gold because prices are at an all-time high and I don’t think it’s a wise investment at the moment. I’m considering shares, bonds, or mutual funds, basically something meaningful, reliable, and within my budget. Her birthday is coming up, and I want this to be a gift that shows her that even if I’m not earning much right now, she will always have something kept aside for her security. My current income is ₹40,000 per month, so I’m looking for an option that won’t create a financial burden.

Also, I would really appreciate a simple explanation, like I’m 12, of how SIPs work.