Edited to say she is managing her own personal care currently. I can see that not being the case for much longer
One piece of advice on this subject @Radionowhere
Do NOT even start to do any personal care. Not even in an emergency. Your DH needs to realise that his mother needs paid carers to do this.
And I'm sure he wouldn't do personal care himself.
So given that there is nobody to do it, your husband will have to give in on this.
And do start looking at care homes, so that you have one ready for when it's inevitably needed. The worst thing would be if your MIL went into hospital, could not be discharged home, and you needed to find a home in an emergency.
Tell your husband and his mother that this is judicious future planning.