If my mom lives with me and I pay all living expenses, can I claim her as a dependent on my taxes?

Very likely you can. You should use a CPA or other financial expert, however, to make sure you do it right.
Carol

As long as you provide at least 50% of the support, you can claim your parent. You can go to your local H&R Block and talk with an experienced preparer.

There is a ton of information at the IRS website:

http://www.irs.gov/pub/irs-pdf/p503.pdf

my elderly father lives with me .I pay for all living expences, can I claim him on my taxes?

my mother is on state pension and lives with me she has no savings can i claim anything