Can I charge my mothers estate for care since she has died?

Tell them they have to be kidding. Tel, them 24/7 care would have at least cost the $10 an hour even for live ins. You did everything. 240 a day about 1600 a week, 6k a month, 70k a year. So, if they want to charge you, you will charge the estate. (They don't have to know you may have needed a caregiver agreement) They may back off because it is ridiculous. If they pursue it, then u may need lawyer. But, its going to cost them to pursue.

What monthly bills are your sibling trying to make you pay for?  Utility bills, grocery bills?  Did you live with your Mom in her house that she owned or in a rental property?  Did your Mom and you co-own a checking account together that you used to pay utility bills and grocery bills?

In regards to charging the Estate for care that you gave to your Mom, such as assistance with ADLs, I doubt that you will get paid unless you had a Caregiver Agreement in writing that both your Mom and you signed and which stated that you would be paid a specific amount of money per hour or per week/month.

Yes you can but you may not be successful.
Did you have any sort of written contract with your mother?