Real Happiness is affording your lifestyle. I would say - "Grandma - no problems helping you out. First, let us get an independent analysis of the situation from an out side source..."
And, yes, the trips to AC, cable and the AARP membership would be the first things on the "can live without" list.
I'm certainly no fan of AARP, but membership is something like $10 a year and it comes with a host of discounts. Assuming that grandma is actually using those discounts (and its something she'd be buying anyway), dropping AARP might be a losing proposition.
I think your approach is reasonable and one that shows genuine concern for the grandmother’s real financial issues. After all, if the shoe was reversed and the grown child was asking for money, you’d naturally expect this to be the reaction from the parent. Yes, we’ll help, but part of helping you is figuring out why you’re having the problem and seeing what can be realistically done to minimize or eliminate it.