I barely could figure out the whole family interrelationships.

..however, don't know of your mother's position or maybe she is not in good health herself.

Seems like your mother should deal with as her mother-in-law. Not certain why you need to shoulder the burden to answer for everyone else in at your location in the country.

Hopefully there are services in the local community for grandmother where she can have a nurse check on her or money to hire someone part-time..

Grandma is laying on the guilt-trip big time.

Good luck!