What is best for my Mom keep original Medicare or enroll into Medicare advantage?

Elder Help: please keep in mind the Medicare ADV plan might not be there NEXT Year
Please Understand there are Combined MED ADV plans that have RX coverage, some that do not, and there are Stand alone RX plans., and she might already be on one.(stand alone Rx Plan)

She is in NY (Queens). She only gets health care from medicare. Per my understanding, her medical is covered by medicare and her secondary medicaid will cover dental and other as well as pay medicare premium.

I thought if i go eith medical advantage plan, it would be one place shopping for her. .. . .meaning, her prescription, dental, etc. Will all be covered by one insurance.

Still struggling to figure out why would i not want to get her into medical advantage plan.

If she already gets Part D coverage, enrollment in a medicare Advantage Plan could get her Part D cancelled!

SO: DO NOT look at an Advantage plan with combined Part D coverage in that case!

Since she just turned 65 she has guaranteed issue with a supplement, a chance she may never get again.!

(She does not have to worry about an Rx Plan since she is covered., as you stated).

Is Medicaid just helping with the 'Health coverage'? I take it that is the case.
A PLAN HDF (High Deductible Plan F pays after the Regular Medicare Deductibles plus another approx $1,200, once that is reached it covers just about everything.
The difference in a Plan F and a HDF is about $150-$250 a month, which the premium savings can be used to pat deductibles for the minor events.

Medicare Advantage plans can have an OOP (out of Pocket) as high as about $6.500, and plans and providers can drop out every year.
The max OOP with the HDF would be $2,160.

pamstegman seems to think or know that you live in NYC and if that is true, that is probably a good answer. But Medicaid differs in every state so the broader answer -- for others -- is "It all depends on where you live. Medicaid rules are different in every state. For example, in my state (Massachusetts), there is no such thing as a Medicaid caseworker."

In addition the choices of Medicare supplements differ in every state, sometimes in every county so it would not be possible to answer on this forum. Sounds like she's out and about so she should make an appointment to talk to a volunteer at the nearest senior center.

If she is Medicaid, she should talk to her caseworker. It would be a Medicaid Advantage Plan, which is managed care. In NYC call 1-800-505-5678 or go to nymedicaidchoice