Neither of those flights will work.

She'll need to get off the plane, go through immigration, collect her bags, go through customs, get over to the domestic terminal, check in, go through security and get to the gate. Not going to happen in 90 minutes, especially with mobility issues. And that's not accounting for a delayed flight - the flight today was 30 minutes late for example.

The terminals aren't connected and will require you to take a train or taxi between the two.

You may be able to check in and drop off luggage in the international terminal but isn't a guarantee. Check with the airline to see if that's a possibility.

Since her flights will be booked on separate tickets (bad move by the way) it's unlikely the airlines will be able to provide much assistance in transferring her. They should be able to get her to the taxi rank at the international terminal at a minimum though. Once checked in for the domestic flight she'll be able to get assistance to the gate. You'll need to contact both airlines though.