Mom in nursing home and the money is running out. I'll apply for Medicaid in June. Should I cancel supplemental insurance after Medicaid is approved?

Medicaid will tell you what health insurance Mom should have, and how it is handled in your state.

As dogperson points out, it will not make any difference to her financially.

When my MIL applied for Medicaid, the social worker said we should keep her supplemental insurance, and that she would be allowed to continue paying for it out of her Social Security. The rest of her income, except for a small personal care allowance, goes toward paying for the nursing home, with Medicaid paying the rest. The social worker said Medicaid would prefer doing it that way even though they would pay more for the nursing home, because the insurance would pay some of her medical expenses. You might want to check with a social worker or Medicaid before you decide what to do.

What kind of supplemental is it? My LO has a supplemental for medications and that premium is covered by Extra Help program, so no charge to her. What Medicare doesn't cover, Supplemental does and then Medicaid would kick in, but, I don't think they ever do on these. I suspect that there are a lot of medications that Medicaid would reject, because they have so many restrictions. If Extra Help didn't cover the medication supplemental, there is no way she could afford it, though, she only keeps a small amount of money from her SS check each month.  As far as her medical care, Medicare pays, and what they don't pay, Medicaid does. That covers it for her and there is no out of pocket charges.  
Maybe, someone around here will know more and chime in.