Can I claim my mother as a dependent if she lives with me?

You might be able, depending on the level of financial support and care you provide. You might also be able to deduct medical expenses from your taxes. The only way to know for sure is to talk to an accountant or financial advisor (or try to deal with the IRS directly!) Here's an article you might like to read on tha topic:
https://www.agingcare.com/109238